WO2011117882A1 - Pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperazine moiety and process for the preparation thereof - Google Patents

Pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperazine moiety and process for the preparation thereof Download PDF

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WO2011117882A1
WO2011117882A1 PCT/IN2011/000181 IN2011000181W WO2011117882A1 WO 2011117882 A1 WO2011117882 A1 WO 2011117882A1 IN 2011000181 W IN2011000181 W IN 2011000181W WO 2011117882 A1 WO2011117882 A1 WO 2011117882A1
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butyl
pyrrolo
methoxy
piperazin
tetrahydro
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PCT/IN2011/000181
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French (fr)
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Kamal Ahmed
Rajesh V. C. R. N. C Shetti
K. Srinivasa Reddy
Adla Malla Reddy
Ponnampally Swapna
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Council Of Scientific & Industrial Research
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Priority to EP11720592.2A priority Critical patent/EP2550275B1/en
Publication of WO2011117882A1 publication Critical patent/WO2011117882A1/en
Priority to US13/525,555 priority patent/US8637665B2/en

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07D—HETEROCYCLIC COMPOUNDS
    • C07D487/00—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00
    • C07D487/02—Heterocyclic compounds containing nitrogen atoms as the only ring hetero atoms in the condensed system, not provided for by groups C07D451/00 - C07D477/00 in which the condensed system contains two hetero rings
    • C07D487/04—Ortho-condensed systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61P—SPECIFIC THERAPEUTIC ACTIVITY OF CHEMICAL COMPOUNDS OR MEDICINAL PREPARATIONS
    • A61P35/00—Antineoplastic agents

Definitions

  • the present invention relates to Pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazole conjuga ential antitumour agent.
  • R H, F, OCF 3 , CF 3 , CI or OMe
  • R 2 OCH 3 or H
  • Present invention also further relates to a process for the preparation of Pyrro!o[2,l-c] [l,4] benzodiazepine - benzothiazole or benzoxazole conjugates linked through piperazine moiety.
  • the present invention further relates to a process for the preparation of 7-Methoxy-8-[n 2 -(4- ⁇ n [3 or 4(l,3-benzothiazol-2-yl)-substitutedphenoxy]alkyl ⁇ piperazin-l-yl)alkyl]oxy-(llaS)-l,2,3, lla-tetrahydro- 5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one and 7-Methoxy-8-[n 2 -(4- ⁇ n [3 or 4(l,3-benzoxazole-2-yl)- substitutedphenoxy]alkyl ⁇ piperazin-l-yl)alkyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2 ; l- c][l,4]benzodiazepin-5-one with aliphatic chain length variations.
  • PBDs Pyrrolo[2,l-c][l,4]benzodiazepines
  • PBD dimers have been developed that comprise of two C2-exo-methylene substituted DC-81 subunits tethered through their C-8 position via an inert propanedioxy linker (Gregson, S. J.; Howard, P. W.; Hartely, J. A.; Brooks, N. A.; Adams, L. J.; Jenkins, T. C; Kelland, L. R. and Thurston, D. E. J. Med. Chem. 2001, 44, 737).
  • a non-cross-linking mixed imine-amide PBD dimers have been synthesized that have significant DNA binding ability and potent antitumour activity (Kamal, A.; Ramesh, G.
  • Benzothiazoles are small synthetic molecules that contain a benzene ring fused to a thiazole ring. These simple molecules have shown remarkable antitumour properties and some of them are undergoing evaluation in clinical trials (Shi, D.-F.; Bradshaw, T. D.; Wrigley, S.; McCall, C. J.; Lelieveld, P.; Fichtner, I.; Stevens, M. F. G. J. Med. Chem. 1996, 39, 3375; Kashiyama, E.; Hutchinson, 1; Chua, M.-S.; Stinson, S. F.; Phillips, L. R.; Kaur, G.; Sausville, E. A.; Bradshaw, T. D.; Westwell, A.
  • benzothiaole and piperazine subunits are considered to be a different heterocyclic moieties compared to the earlier reported pharmacophores like napthalimide. Therefore, this structural variation of benzothiazole with piperazine moiety has been utilized for DNA binding aspect. Keeping this in mind, these new conjugates have been designed and synthesized to further improve the anticancer activity including the DNA binding affinity. The anticancer activity may not depend on the DNA binding activity. The DNA binding activity is only, a biophysical aspect, therefore comparison of this data has no significance for the biological profile of the compounds. The new molecules of the present investigation exhibit potential anticancer activity.
  • potent conjugate 9f (IICT-302) of this series has been evaluated for its in vivo efficacy studies (in scid male mice) against MCF-7 (breast cancer) and PC-3 (prostate cancer) xenografts by using adriamycin as a positive control.
  • the in vivo efficacy study of 9f has exhibited less toxicity, good survival data and good RTV then control adriamycin indicating the potential use of these molecules in treating cancer.
  • the main objective of the present invention is to provide Pyrrolo[2,l-c][l,4]benzodiazepine- benzothiazole or benzoxazole conjugates linked through piperazine moiety useful as antitumour agents.
  • Yet another object of the present invention is to provide a process for the preparation of Pyrrolo [2,1- c] [l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperazine moiety.
  • present invention provides Pyrrolo [2, 1-c] [1,4] benzodiazepine - benzothiazole or
  • R, Ri H, F, OCF 3 , CF 3 , CI or OMe;
  • R 2 OCH3 or H
  • representative compounds of general formula 9 are:
  • said compounds are useful as anticancer agent.
  • said compounds exhibiting in-vitro anticancer activity against human cancer cell lines derived from nine cancer types of leukemia cancer cell line, non- small-cell lung cancer cell line, colon cancer cell line, CNS cancer cell line, melanoma cancer cell line, ovarian cancer cell line, prostate cancer cell line, and breast cancer cell line.
  • concentration of the compound 9a-l used for in- vitro activity against breast (MCF-7) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.14 ⁇ and ⁇ 0.01 to 2.6 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against colon (Colo205) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.17 ⁇ and >10 2 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against non small cell lung (A549) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.13 ⁇ and 30 to >10 2 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against non small cell lung (HOP 62) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.16 ⁇ and 2.3 to >10 2 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against ovarian (A 2780) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.147 ⁇ and 0.089 to 23 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against prostate (Pc 3) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to ⁇ . ⁇ and 0.23 to 31 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against cervix (SiHa) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.168 ⁇ and 0.311 to 28.5 ⁇ respectively at an exposure period of at least 48 hrs.
  • concentration of the compound 9a-l used for in- vitro activity against oral (KB) cancer cell line for Gl 50 and LC 50 are in the range of ⁇ 0.01 to 0.16 ⁇ and 0.18 to >10 2 ⁇ respectively at an exposure period of at least 48 hrs.
  • a process for the preparation of pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperzine of general formula 9 and the said process comprising the steps of :
  • step (iv) etherifying precursors as obtained in step (iv) with dibromoalkanes in presence of K 2 C0 3 in acetone at 80 °C for 12 h to obtain benzothiazole /benzoxazole precursors of formula 6a-z;
  • step (iii) reacting a compound of formula 4a-b as obtained in step (iii) with benzothiazole or benzoxazole derivative selected from the compound of formula 6a-z as obtained in step (v) in the presence of K 2 C0 3 , in acetone solvent, under refluxing temperature in the ran e of 70-75 °C to obtain the resultant nitro compound of formula 7a-z;
  • step (vi) reducing the above said nitro compound of formula 7a-z as obtained in step (vi) with SnCI 2 .2H 2 0 in methanol solvent, under reflux temperature in the range of 80-85 °C and isolati
  • step (viii) reacting the above said amino compound of formula 8 as obtained in step (vii) with a deprotecting agent etanethiol/BF 3 .OEt 2 by known method to obtain the desired compound of formula 9.
  • a process for the preparation of pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazote conjugates linked through piperzine of general formula 9 and the said process comprising the steps of :
  • step (b) reducing the above said nitro compound of formula 7a-z as obtained in step (a) with SnCI 2 .2H 2 0 in methanol solvent, under reflux temperature in the range of 80-85 °C and isolating the corresponding amino compound of formula 8a-z;
  • step (b) reacting the above said amino compound of formula 8 as obtained in step (b) with a deprotecting agent etanethiol/BF 3 .OEt 2 by known method to obtain the desired compound of formula 9.
  • Scheme 1 shows the synthesis of benzothiozole/benzoxazole-PBD conjugates (9a-c; 9e-g; 9i-j; 91-m and 9p-z) linked through Piperazine moiety.
  • Compounds 4a or 4b has been coupled to 6a-c; 6e-g; 6i-j; 61-m and 6p-z to give corresponding nitrothioacetals 7a-c; 7e-g; 7i-j; 71-m and 7p-z respectively.
  • These coupled nitrothioacetal intermediates reduced with SnCI 2 .2H 2 0 in methanol affords amino thioacetal precursors 8a-c; 8e-g; 8i-j; 81-m and 8p-z.
  • This on deportation by HgCI 2 /CaC0 3 affords desire PBD conjugates 9a-c; 9e-g; 9i-j; 91-m and 9p-z.
  • Scheme 2 shows the synthesis of benzothiozole/benzoxazole-PBD conjugates (9d, 9h, 9k, 9n or 9o) linked through Piperazine moiety.
  • Compounds 4a or 4b has been coupled to 6d, 6h, 6k, 6n or 6o to give corresponding nitrothioacetals 7d, 7h, 7k and 7n,o respectively.
  • These coupled nitrothioacetal intermediates reduced with SnCI 2 .2H 2 0 in methanol affords amino thioacetal precursors 8d, 8h, 8k, 8n or 8o.
  • This on deportation by HgCI 2 /CaC0 3 affords desire PBD conjugates 9d, 9h, 9k and 9n or 9o.
  • Figure 1 represent some compounds of formula 1, 2a-b, 3a-b and 5a-s.
  • Figure 2 represents In vivo efficacy study of compound 9f on xenograft MCF-7.
  • Figure 3 represents In vivo efficacy study of compound 9f on xenograft PC3.
  • the benzoxazole precursors 5e-g and 5o-s have been prepared by condensation of 2-aminophenols with benzylated protected benzaldehydes, oxidation followed by debenzylation with palladium on charcoal (Centore, R.; Panunzi, B.; Roviello, A.; Sirigu, A.; Villano, P. J. Polym. Sci. Part A: Polym. Chem. 1996, 34, 3203).
  • the benzothiazole /benzoxazole precursors (formula 6a-z) have been prepared by etherfication reaction between compounds 5a-s and dibromoalkanes in presence of K 2 C0 3 in acetone at 80 °C for 12 h.
  • the precursors 5a-d and 5h-5n have been prepared by the condensation of substituted 2- aminothiophenol with 4-hydroxy benzaldehyde, 3-hydroxy benzaldehyde, vanilline or isovanillline.
  • the benzoxazole precursors 5e-g and 5o-s have been prepared by condensation of 2-aminophenols with benzylated protected benzaldehydes, oxidation followed by debenzylation with palladium on charcoal.
  • the benzothiazole /benzoxazole precursors (formula 6a-z) have been prepared by etherfication reaction between compounds 5a-s and dibromoalkanes in presence of K 2 C0 3 in acetone at 80 °C for 12 h.
  • Table 4 Comparative in vitro cytotoxicity data of benzothiazole and benzoxazle linked PBD hybrids with piperizine and with, out piperizine in selected human cancer cell lines (Gl 50 values 3 in ⁇ concentration)
  • Table 5 Comparative in vitro cytotoxicity data of benzothiazole and benzoxazle linked PBD hybrids with piperizine and with out piperizine in selected human cancer cell lines (Gl 50 values 9 in ⁇ concentration)
  • ADR 0.19 13 ⁇ 0.01 0.16 a 50% Growth inhibition and the values are mean of three determinations, b brest cancer, c ovary cancer, d colon cancer, e prostate cancer, f cervix cancer, 6 lung cancer, h oral cancer, ADR, adriamycin
  • CT-DNA duplex-form calf thymus DNA
  • T m DNA heii — coil transition temperatures
  • T m 69.1 °C ⁇ 0.01 (mean value from 10 separate determinations)
  • all AT m values are ⁇ 0.1 - 0.2 °C.
  • Anticancer activity In vitro biological activity studies were carried out at the Advance Center for Treatment Research & Education in Cancer (ACTREC), Navi Mumbai.
  • the compounds were evaluated for in vitro anticancer activity against eight tumour cells lines derived from seven cancer types (non-small-cell lung, colon, oral, cervix, ovarian, prostate, and breast cancer) as shown in Table 2.
  • dose response curves for each cell line were measured at a minimum pf five concentrations at 10 fold dilutions.
  • a protocol of 48 h continuous drug exposure was used and a sulforhodamine B (SRB) protein assay was used to estimate cell viability or growth.
  • the concentration causing 50% cell growth inhibition (GI50) and 50% cell death (LC 50 , -50% growth) compared with the control was calculated.
  • Colo 205 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2 >10 2
  • the compounds prepared in this invention have shown remarkable cytotixic activity against cancer cell lines.
  • 9a exhibit Gl 50 ranging from 0.13 to ⁇ 0.01 ⁇ .
  • 9b exhibit GI50 ranging from 0.12 to ⁇ . ⁇
  • 9c exhibit GI50 ranging from 0.13to ⁇ . ⁇
  • 9d exhibit GI50 ranging from 0.12 to ⁇ 0.01 ⁇ ;
  • 9e exhibit GI50 ranging from 0.12 to ⁇ 0.01 ⁇
  • 9f exhibit GI50 ⁇ 0.01 ⁇
  • 9g exhibit GI50 ranging from 0.168 to ⁇ . ⁇
  • 9h exhibit GI50 ranging from 0.16 to ⁇ 0.1 ⁇
  • 9i exhibit GI50 ranging from 0.117 to ⁇ 0.01 ⁇
  • 9j exhibit GI50 ranging from 0.11 to ⁇ 0.01 ⁇
  • 9k exhibit GI50 ranging from 0.17 to ⁇ 0.01 ⁇
  • 91 exhibit GI50 ranging from 0.125 to ⁇ 0.01 ⁇ respectively.

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Abstract

The present invention provides a compound of general formula 9, useful as potential antitumour agents against human cancer cell lines. The present invention further provides a process for the preparation of Pyrrolo[2,l-c][l,4]benzodiazepine - benzothiazole or benzoxazole conjugates linked through piperazine of general formula (9) wherein: R, R1 = H, F, OCF3, CI, OMe; R2 = OCH3 or H; n1 n2= 3, 4; x = S or O

Description

PYRROLO[2,l-C][l,4]BENZODIAZEPINE-BENZOTHIAZOLE OR BENZOXAZOLE CONJUGATES LINKED THROUGH PIPERAZINE MOIETY AND PROCESS FOR THE PREPARATION THEREOF
FIELD OF THE INVENTION
The present invention relates to Pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazole conjuga ential antitumour agent.
Figure imgf000002_0001
GENERAL FORMULA 9
Wherein: R, = H, F, OCF3, CF3, CI or OMe;
R2 = OCH3 or H;
n1( n2= 3 or 4;
X = S or O.
Present invention also further relates to a process for the preparation of Pyrro!o[2,l-c] [l,4] benzodiazepine - benzothiazole or benzoxazole conjugates linked through piperazine moiety.
The present invention further relates to a process for the preparation of 7-Methoxy-8-[n2-(4-{n [3 or 4(l,3-benzothiazol-2-yl)-substitutedphenoxy]alkyl}piperazin-l-yl)alkyl]oxy-(llaS)-l,2,3, lla-tetrahydro- 5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one and 7-Methoxy-8-[n2-(4-{n [3 or 4(l,3-benzoxazole-2-yl)- substitutedphenoxy]alkyl}piperazin-l-yl)alkyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2;l- c][l,4]benzodiazepin-5-one with aliphatic chain length variations.
BACKGROUND OF THE INVENTION
Pyrrolo[2,l-c][l,4]benzodiazepines (PBDs), a group of potent naturally occurring antitumour antibiotics from various Streptomyces species, are of considerable interest because of their ability to recognize and subsequently form covalent bonds to specific base sequence of double strand DNA (Dervan, P. B. Science 1989, 232, 464.; Hurley, L. H. J. Med. Chem. 1989, 32, 2027.; Thurston, D. E.; Thompson/ A. S. Chem. Br. 1990, 26, 767). Well-known members of this group include anthramycin, DC-81, sibiromycin, tomamycin, chicamycin and neothramycin.of A and B (Hurley, L. H. J. Antibiot. 1977, 30, 349.; Schimizu, K.; Kawamoto, I.; Tomita, F.; orimoto, M.; Fujimoto, K. J. Antibiot. 1982, 35, 992,; Lown, J. W.; Joshua, A. V. Biochem. Pharmacol. 1979, 28, 2017.; Thurston, D. E.; Bose, D. S. Chem. Rev. 1994, 94, 433.; Molina, P.; Diaz, I.; Tarraga, A. Tetrahedron 1995, 51, 5617.; Kamal, A.; Rao, N. V. Chem. Commun. 1996, 385.; Kamal, A.; Redely, B. S. P.; Reddy, B. S. N. Tetrahedron Lett. 1996, 37, 6803). The cytotoxicity and antitumour activity of these agents are attributed to their property of sequence selective covalent binding to the N2 of guanine in the minor groove of duplex DNA via an acid-labile aminal bond to the electrophilic imine at the N10-C11 position (Kunimoto, S.; Masuda, T.; Kanbayashi, N.; Hamada, M.; Naganawa, H.; Miyamoto, M.; Takeuchi, T.; Unezawa,. H. J. Antibiot, 1980, 33, 665.; Kohn, K. W. and Speous, C. L. J. Mol. Biol., 1970, 51, 551.; Hurley, L. H.; Gairpla, C. and Zmijewski, M. Biochem. Biophys. Acta., 1977, 475, 521.; Kaplan, D. J. and Hurley, L. H. Biochemistry, 1981, 20, 7572). The molecules have a right-handed twist, which allows them to follow the curvature of the minor groove of B-form double- stranded DNA spanning three base pairs. A recent development has been the linking of two PBD units through their C-8 positions to give bisfunctional-alkylating agents capable of cross-linking DNA (Thurston, D. E.; Bose, D. S.; Thomson, A. S.; Howard, P. W.; Leoni, A.; Croker, S. J.; Jenkins, T. C; Neidle, S. and Hurley, L. H. J. Org. Chem. 1996, 61, 8141).
Figure imgf000003_0001
Recently, PBD dimers have been developed that comprise of two C2-exo-methylene substituted DC-81 subunits tethered through their C-8 position via an inert propanedioxy linker (Gregson, S. J.; Howard, P. W.; Hartely, J. A.; Brooks, N. A.; Adams, L. J.; Jenkins, T. C; Kelland, L. R. and Thurston, D. E. J. Med. Chem. 2001, 44, 737). A non-cross-linking mixed imine-amide PBD dimers have been synthesized that have significant DNA binding ability and potent antitumour activity (Kamal, A.; Ramesh, G. Laxman, N.; Ramulu, P.; Srinivas, O.; Neelima, K.; Kondapi, A. K.; Srinu, V. B.; Nagarajaram, H. M. J. Med. Chem. 2002, 45, 4679). However, the clinical efficacy for these antibiotics is hindered by several limitations, such as poor water solubility, cardiotoxicity, development of drug resistance and metabolic inactivation. Due to the excellent activity of these molecules, there is need to develop novel derivatives which are devoid of above limitations.
Benzothiazoles are small synthetic molecules that contain a benzene ring fused to a thiazole ring. These simple molecules have shown remarkable antitumour properties and some of them are undergoing evaluation in clinical trials (Shi, D.-F.; Bradshaw, T. D.; Wrigley, S.; McCall, C. J.; Lelieveld, P.; Fichtner, I.; Stevens, M. F. G. J. Med. Chem. 1996, 39, 3375; Kashiyama, E.; Hutchinson, 1; Chua, M.-S.; Stinson, S. F.; Phillips, L. R.; Kaur, G.; Sausville, E. A.; Bradshaw, T. D.; Westwell, A. D.; Stevens, M. F. G. J. Med. Chem. 1999, 42, 4172; Hutchinson, I.; Chua, M.-S.; Browne, H. L; Trapani, V.; Bradshaw, T. D.; Westwell, A. D.; Stevens, M. F. G. J. Med. Chem. 2001, 44, 1446). Recently Westwell and coworkers have prepared a series of benzothiazole derivatives and evaluated for anticancer activity, One of these analogues has shown excellent anticancer activity (Mortimer, C. G.; Wells, G.; Crochard, J. -P.; Stone, E. L; Bradshaw, T. D.; Stevens, M. F. G.; Westwell, A. D. J. Med. Chem. 2006, 49, 179). The structurally related benzoxazoles have also been reported to possess anticancer activity (Kumar, D.; Jacob, M. R.; Reynold, M. B.; Kerwin, S. M. Bioorg. Med. Chem. 2002, 10, 3994; Gong, B.; Hong, F.; Kohm, C; Bonham, L; Klein, P. Bioorg. Med. Chem. Lett. 2004, 14, 1455). During earlier studies in this laboratory PBDs have been linked to benzothiazole or benzoxazole through alkane chain, which have shown promising anticancer activity. (Kamal, A.; Reddy K. S.; Ahmed K. M. N.; Shetti R. V. C. R. N. C International Publication No WO 2008/099416 A2). However, in the present invention the PBD and benzothiazole or benzoxazole moieties have been linked through piperazine moiety with alkyl side arms, instead simple alkane chain spacers. By incorporation of a piperazine moiety in the spacer these new hybrids not only exhibit enhanced in vitro activity but also remarkable DNA binding affinity for a number of this type of hybrids as illustrated in Table 1 and 2.
References may be made to patent "WO/2008/099416" wherein Benzothiazole or benzoxazole linked Pyrrolo[2,l-c][l,4] benzodiazepine hybrid as anticancer agent has been reported. References may be made to patent "US6979684" wherein Pyrrolo[2,l-c][l,4] benzodiazepine and naphthalimide are linked through piperazine moiety. The linking of pharmacophore like napthalimide and piperazine to pyrrolobenzodiazepine can not be considered similar to a pharmacophore like benzothiazole as each pharmacophore is known for certain biological property. In the present investigation the benzothiaole and piperazine subunits are considered to be a different heterocyclic moieties compared to the earlier reported pharmacophores like napthalimide. Therefore, this structural variation of benzothiazole with piperazine moiety has been utilized for DNA binding aspect. Keeping this in mind, these new conjugates have been designed and synthesized to further improve the anticancer activity including the DNA binding affinity. The anticancer activity may not depend on the DNA binding activity. The DNA binding activity is only, a biophysical aspect, therefore comparison of this data has no significance for the biological profile of the compounds. The new molecules of the present investigation exhibit potential anticancer activity. Moreover, one of the potent conjugate 9f (IICT-302) of this series has been evaluated for its in vivo efficacy studies (in scid male mice) against MCF-7 (breast cancer) and PC-3 (prostate cancer) xenografts by using adriamycin as a positive control. The in vivo efficacy study of 9f has exhibited less toxicity, good survival data and good RTV then control adriamycin indicating the potential use of these molecules in treating cancer.
OBJECTIVES OF THE INVENTION
The main objective of the present invention is to provide Pyrrolo[2,l-c][l,4]benzodiazepine- benzothiazole or benzoxazole conjugates linked through piperazine moiety useful as antitumour agents. Yet another object of the present invention is to provide a process for the preparation of Pyrrolo [2,1- c] [l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperazine moiety.
SUMMARY OF THE INVENTION
Accordingly, present invention provides Pyrrolo [2, 1-c] [1,4] benzodiazepine - benzothiazole or
nzoxazole conjugates linked through piperzine moiety of general formula 9,
Figure imgf000005_0001
GENERAL FORMULA 9
Wherein: R, Ri = H, F, OCF3, CF3, CI or OMe;
R2 = OCH3 or H;
n1( n2= 3 or 4;
X = S or O.
In an embodiment of the present invention, representative compounds of general formula 9 are:
7-Methoxy-8-[3-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyl] oxy-(llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9a);
7-Methoxy-8-[3-(4-{4-[3(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]propyl} piperazin-l-yl)propyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9b);
7-Methoxy-8-[3-(4-{4-[3(6-flouro-l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl)propyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9c);
7-Methoxy-8-[3-(4-{3-[3(l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyl]oxy-( llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9d); 7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl]oxy-(llaS)-l,2,3,lla- tetrahydro-5H-pyrrolo[2, l-c] [l,4]benzodiazepin-5-one (9e);
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-l-yl)butyl]oxy- (lla5)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9f);
7-Methoxy-8-[4-(4-{4-[4(6-fluoro-l,3-benzothiazol-2-yl)-phenoxy] butyl}piperazin-l-yl)butyl]oxy-(llaS)- l,2,3;lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9g);
7-Methoxy-8-[4-(4-{4-[3( l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl]oxy-(lla5)-l,2,3,lla- tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9h).
7-Methoxy-8-[3-(4-{4-[3(l,3-benzoxazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyl]oxy-(llaS)- l,2,3,Ha-tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9i);
7-Methoxy-8-[3-(4-{4-[3(l,3-benzoxazol-2-yl)-2-methoxyphenoxy]propyl} piperazin-l-yi)propyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l;4] benzodiazepin-5-one (9j);
7-Methoxy-8-[3-(4-{3-[3(l,3-benzoxazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5W-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9k);
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl]oxy-( llaS)-l,2,3,lla- tetrahydro-5/-/-pyrrolo[2, l-c] [l,4]benzodiazepin-5-one (91);
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-2-methoxyphenoxy] butyl} piperazin-l-yl)butyl]oxy- (lla5)-l,2,3,lla-tetrahydro-5H-pyrrolo[2;l-c] [l,4] benzodiazepin-5-one (9m);
7-Methoxy-8-[4-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl]oxy-(llaS)-l,2,3,lla- tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one(9n);
7-Methoxy-8-[4-(4-{3-[4( l,3-benzothiazol-2-yl)-4-methoxyphenoxy]butyl} piperazin-l-yl)butyl]oxy- (llaS)-l,2,3;lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9o);
7-Methoxy-8-[4-(4-{4-[4(6-trifluoromethyl-l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl}piperazin-l- yl)butyl]oxy-(lla5)-l,2/3 lla-tetrahydro-5H-pyrrolo[2 l-c][l,4]benzodiazepin-5-one (9p);
7-Methoxy-8-[4-(4-{4-[4(6-trifluoromethoxy-l,3-benzothiazol-2-yl)-2-methoxy
phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l- c] [l,4]benzodiazepin-5-one (9q);
7-Methoxy-8-[4-(4-{4-[4(6-methoxy-l,3-benzothiazol-2-yl)-2-methoxyphenoxy] butyl}piperazin-l- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9r);
7-Methoxy-8-[4-(4-{4-[4(5-fluoro-l,3-benzothiazol-2-yl)-2-methoxyphenoxy] butyl} piperazin-1- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2, l-c] [l,4] benzodiazepin-5-one (9s); 7-Methoxy-8-[4-(4-{4-[4(6-chloro-l,3-benzothiazol-2-yl)-2-methoxyphenoxy] butyl}piperazin-l- yl)butyl]oxy-(llaS)-l;2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9t);
7-Methoxy-8-[4-(4-{4-[4(5-fluoro-l/3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2;l-c] [l;4]benzodiazepin-5-one (9u);
7-Methoxy-8-[4-(4-{4-[4(6-methoxy-l,3-benzoxazol-2-yl)-2-methoxyphenoxy] butyl}piperazin-l- yl)butyl]oxy-(llaS)-l,2,3,Ha-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9v);
7-Methoxy-8-[4-(4-{4-[4(6-trifluoromethoxy-l,3-benzoxazol-2-yl)-2-methoxyphenoxy]butyl}piperazin-l- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5W-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9w);
7-Methoxy-8-[4-(4-{4-[4(6-fluoro-l,3-benzoxazol-2-yl)-2-methoxyphenoxy] butyl} piperazin-1- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9x);
7-Methoxy-8-f4-(4-{4-[4(5-fluoro-l,3-benzoxazol-2-yl)-2-methoxyphenoxy] butyl} piperazin-1- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9y);
7-Methoxy-8-[4-(4-{4-[4(6-chloro-l,3-benzoxazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-1- yl)butyl]oxy-( lla5)-l,2,3,Ha-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9z).
In yet another embodiment of the present invention, structural formula of the representative compound
Figure imgf000007_0001
Figure imgf000008_0001
Figure imgf000009_0001
Figure imgf000009_0002
Figure imgf000009_0003
Figure imgf000010_0001
Figure imgf000010_0002
(9z)
In yet another embodiment of the present invention, said compounds are useful as anticancer agent. In yet another embodiment of the present invention, said compounds exhibiting in-vitro anticancer activity against human cancer cell lines derived from nine cancer types of leukemia cancer cell line, non- small-cell lung cancer cell line, colon cancer cell line, CNS cancer cell line, melanoma cancer cell line, ovarian cancer cell line, prostate cancer cell line, and breast cancer cell line.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against breast (MCF-7) cancer cell line for Gl50 and LC50 are in the range of <0.01 to 0.14μηΊ and <0.01 to 2.6μηι respectively at an exposure period of at least 48 hrs. In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against colon (Colo205) cancer cell line for Gl50 and LC50 are in the range of <0.01 to 0.17 μηι and >102μηι respectively at an exposure period of at least 48 hrs.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against non small cell lung (A549) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.13μηι and 30 to >102 μιτι respectively at an exposure period of at least 48 hrs.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against non small cell lung (HOP 62) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.16μιη and 2.3 to >102 μιτι respectively at an exposure period of at least 48 hrs.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against ovarian (A 2780) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.147μηι and 0.089 to 23 μιη respectively at an exposure period of at least 48 hrs.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against prostate (Pc 3) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to Ο.ΐβμηη and 0.23 to 31 μιη respectively at an exposure period of at least 48 hrs.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against cervix (SiHa) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.168 μηι and 0.311 to 28.5 μιη respectively at an exposure period of at least 48 hrs.
In yet another embodiment of the present invention, concentration of the compound 9a-l used for in- vitro activity against oral (KB) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.16μηι and 0.18 to >102 μιη respectively at an exposure period of at least 48 hrs.
In an embodiment, a process for the preparation of pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperzine of general formula 9 and the said process comprising the steps of :
i. etherifying compound of formula 1 with dibromo alkanes in acetone reflux at 80 °C for
12
Figure imgf000011_0001
2a (n=3) 2b (n=4) coupling compound of formula 2a, b as obtained in step (i) with /V-Boc piperazine acetone reflux at 80 °C for 24 h to produce 3a,b;
Figure imgf000012_0001
3a-b
3a (n=3) 3b (n=4)
iii. deprotecting compound of formula 3a, b by using Trifluoroacetic acid (TFA)at 27 °C for 12 h to obtain compounds of formula 4a-b;
Figure imgf000012_0002
4a-b
4a (n=3) 4b (n=4) iv. condensing substituted 2-aminothiophenol or 2-aminophenols with 4-hydroxy benzaldehyde, 3-hydroxy benzaldehyde, vanilline, isovanillline or benzylated protected benzaldehydes, oxidation followed by debenzylation with palladium on charcoal to obtain to obtain precursors 5a-s;
Figure imgf000012_0003
v. etherifying precursors as obtained in step (iv) with dibromoalkanes in presence of K2C03 in acetone at 80 °C for 12 h to obtain benzothiazole /benzoxazole precursors of formula 6a-z;
Figure imgf000013_0001
6 a, b, c, e, f, g, I, j, I, m, p-z 6 d, h, k, n, o
vi. reacting a compound of formula 4a-b as obtained in step (iii) with benzothiazole or benzoxazole derivative selected from the compound of formula 6a-z as obtained in step (v) in the presence of K2C03, in acetone solvent, under refluxing temperature in the ran e of 70-75 °C to obtain the resultant nitro compound of formula 7a-z;
Figure imgf000013_0002
vii. reducing the above said nitro compound of formula 7a-z as obtained in step (vi) with SnCI2.2H20 in methanol solvent, under reflux temperature in the range of 80-85 °C and isolati
Figure imgf000013_0003
viii. reacting the above said amino compound of formula 8 as obtained in step (vii) with a deprotecting agent etanethiol/BF3.OEt2 by known method to obtain the desired compound of formula 9. In an embodiment, a process for the preparation of pyrrolo[2,l-c][l,4]benzodiazepine-benzothiazole or benzoxazote conjugates linked through piperzine of general formula 9 and the said process comprising the steps of :
a.
Figure imgf000014_0001
4a-b
4a (n=3) 4b (n=4)
with benzothiazole or benzoxazole derivative selected from the compound of formula 6a-z
Figure imgf000014_0002
6 a, b, c, e, f, g, I, j, I, m, p-z 6 d, h, k, n, o
in the presence of K2C03, in acetone solvent, under refluxing temperature in the range of 70-75 °C to obtain the resultant nitro compound of formula 7a-z;
Figure imgf000014_0003
b. reducing the above said nitro compound of formula 7a-z as obtained in step (a) with SnCI2.2H20 in methanol solvent, under reflux temperature in the range of 80-85 °C and isolating the corresponding amino compound of formula 8a-z;
Figure imgf000015_0001
c. reacting the above said amino compound of formula 8 as obtained in step (b) with a deprotecting agent etanethiol/BF3.OEt2 by known method to obtain the desired compound of formula 9.
BRIEF DESCRIPTION OF THE DRAWINGS
Scheme 1 shows the synthesis of benzothiozole/benzoxazole-PBD conjugates (9a-c; 9e-g; 9i-j; 91-m and 9p-z) linked through Piperazine moiety. Compounds 4a or 4b has been coupled to 6a-c; 6e-g; 6i-j; 61-m and 6p-z to give corresponding nitrothioacetals 7a-c; 7e-g; 7i-j; 71-m and 7p-z respectively. These coupled nitrothioacetal intermediates reduced with SnCI2.2H20 in methanol affords amino thioacetal precursors 8a-c; 8e-g; 8i-j; 81-m and 8p-z. This on deportation by HgCI2/CaC03 affords desire PBD conjugates 9a-c; 9e-g; 9i-j; 91-m and 9p-z.
Scheme 2 shows the synthesis of benzothiozole/benzoxazole-PBD conjugates (9d, 9h, 9k, 9n or 9o) linked through Piperazine moiety. Compounds 4a or 4b has been coupled to 6d, 6h, 6k, 6n or 6o to give corresponding nitrothioacetals 7d, 7h, 7k and 7n,o respectively. These coupled nitrothioacetal intermediates reduced with SnCI2.2H20 in methanol affords amino thioacetal precursors 8d, 8h, 8k, 8n or 8o. This on deportation by HgCI2/CaC03 affords desire PBD conjugates 9d, 9h, 9k and 9n or 9o.
Figure 1 represent some compounds of formula 1, 2a-b, 3a-b and 5a-s.
Figure 2 represents In vivo efficacy study of compound 9f on xenograft MCF-7.
Figure 3 represents In vivo efficacy study of compound 9f on xenograft PC3.
DETAILED DESCRIPTION OF THE INVENTION
The precursors (2S)-N-[4-(hydroxy-5-methoxy-2-nitrobenzoyl]pyrrolidine-2-carboxaldehyde diethyl thioacetal of formula 1 (Thurston, D. E.; Murthy, V. S.; Langley, D. R.; Jones, G. B. Synthesis. 1990, 81), (2S)-[N-{4-(3-(piperzin-l-yl)alkyl)-5-methoxy-2-nitro benzoyl] pyrrolidine-2-carboxaldehyde diethylthioacetal of formula 4a,b (Ahmed Kamal, M. Naseer A. Khan, K. Srinivasa Reddy, S. Kaleem Bio- Med Chem Lett 2007, 17, 5345-5348) and the 4/3-(l,3-benzothiazol-2-yl-5/6-alkyl/alkoxy/halo)phenol / 4/3-(l,3-benzothiazol-2-yl-5/6-alkyl/alkoxy/halo)-2-methoxyphenol of formula 5a-d and 5h-5n have been prepared by literature methods (Ben-Allum, A.; Bakkas, S.; Soufiaoui, M. Tetrahedron Lett. 1997, 38, 6395; Wells, G.; Lowe, P. R.; Stevens, M. F. G. ARKIVOC 2000, 1, 779). The benzoxazole precursors 5e-g and 5o-s have been prepared by condensation of 2-aminophenols with benzylated protected benzaldehydes, oxidation followed by debenzylation with palladium on charcoal (Centore, R.; Panunzi, B.; Roviello, A.; Sirigu, A.; Villano, P. J. Polym. Sci. Part A: Polym. Chem. 1996, 34, 3203). The benzothiazole /benzoxazole precursors (formula 6a-z) have been prepared by etherfication reaction between compounds 5a-s and dibromoalkanes in presence of K2C03 in acetone at 80 °C for 12 h.
Synthesis of compound 1 has been carried out by employing commercially available vanillin. Oxidation of vanillin, followed by benzylation and nitration provides 4-benzyloxy-5-methoxy-2-nitrobenzoic acid. This has been further coupled to L-Proline methyl ester, which upon reduction with DIBAL-H produces the corresponding aldehyde. The aldehyde group of this product has been protected with EtSH/T SCI and upon debenzylation affords (2S)-W~[4-hydroxy-5-methoxy-2-nitrobenzoyl]pyrolidine-2- carboxaldehyde diethyl thioacetal (formula 1) by employing literate methods, which upon etherification by dibromo alkanes affords 2a,b in acetone reflux (80 °C) for 12 h. These compounds have been coupled to /V-Boc piperazine in acetone reflux (80 °C) for 24 h to produce 3a,b. The compounds 3a,b has been deprotected by using TFA affords compounds 4a,b at 27 °C for 12 h.
The precursors 5a-d and 5h-5n have been prepared by the condensation of substituted 2- aminothiophenol with 4-hydroxy benzaldehyde, 3-hydroxy benzaldehyde, vanilline or isovanillline. The benzoxazole precursors 5e-g and 5o-s have been prepared by condensation of 2-aminophenols with benzylated protected benzaldehydes, oxidation followed by debenzylation with palladium on charcoal. The benzothiazole /benzoxazole precursors (formula 6a-z) have been prepared by etherfication reaction between compounds 5a-s and dibromoalkanes in presence of K2C03 in acetone at 80 °C for 12 h.
These pyrrolo[2,l-c][l,4]benzodiazepine hybrids linked at C-8 position have shown promising DNA binding activity and efficient anticancer activity in various cell lines. The molecules synthesized are of immense biological significance with potential sequence selective DNA-binding property. Process steps are:
1) The ether linkage at C-8 position of DC-81 intermediates with benzothiazole and benzoxazole moieties.
2) Refluxing the reaction mixtures for 48 h. 3) Synthesis of C-8 linked PBD antitumour antibiotic hybrid imines.
4) Purification by column chromatography using different solvents like ethyl acetate, hexane, chloroform and methanol.
Table 1. Representative formulas of hydroxybenzothiazloe/benzoxazole intermediates.
Figure imgf000017_0001
Table 2. Representative formulas of benzothiazloe/berizoxazole intermediates.
Figure imgf000017_0002
Figure imgf000018_0001
COMPARATIVE DATA
Table 3. Comparative data of DNA binding affinity of benzothiazole and benzoxazole linked PBD hybrids with piperizine and with out piperizine.
Figure imgf000018_0002
20a 0.5 0.5 9a 10.2 10.8
20b 0.5 0.5 9b 12.1 12.7
20c 4.1 4.3 9c 10.3 10.7
20d 6.2 6.3 9d 11.2 11.5
23b 0.5 0.5 9e 12.2 12.6
26 2.1 4.2 9f 15.5 15.9
30a 4.1 4.3 9g 12.3 12.6
30b 4.2 4.3 9h 11.9 12.3
9i 9.5 9.7
9j 10.1 10.3
9k 9.7 10.2
91 11.5 11.8
9 m 12.1 12.5
9n 10.3 10.6
DC-81 0.3 0.7 a For CT-DNA alone at pH 7.00 ± 0.01, Tm = 69.1 °C ± 0.01 (mean value from 10 separate determinations), all Afm values are ± 0.1 - 0.2 °C. b For a 1:5 molar ratio of [PBD]/[DNA], where CT-DNA concentration = 100 μΜ and ligand concentration = 20 μΜ in aqueous sodium phosphate buffer [10 mM sodium phosphate + 1 mM EDTA, pH 7.00 ± 0.01].
Table 4 : Comparative in vitro cytotoxicity data of benzothiazole and benzoxazle linked PBD hybrids with piperizine and with, out piperizine in selected human cancer cell lines (Gl50 values3 in μΜ concentration)
hybrides Hybrides
MCF Colo Colo
with out IGROV PC 3e with MCF 7b A 2780° PC 3e
7b 205 d 205 d piperazine piperazine
20a 0.32 2.42 0.34 0.29 9a <0.01 0.108 0.1 0.12
20b 0.40 3.06 0.69 0.41 9b <0.01 <0.01 0.09 <0.01
20c 0.33 2.69 0.38 • 0.23 9c <0.01 0.116 0.13 0.11
20d 0.01 0.344 0.06 0.04 9d 0.01 0.099 0.11 <0.01
9e <0.01 0.097 0.12 <0.01
9f <0.01 <0.01 <0.01 <0.01
9g 0.14 0.147 0.1 0.16
9h 0.12 0.109 0.16 0.14
9i <0.01 0.08 <0.01 <0.01
9j <0.01 <0.01 0.11 <0.01
9k <0.01 10.086 0.17 <0.01
91 <0.01 0.099 <0.01 <0.01
DC-81 0.16 0.13 0.10 -
ADR <0.01 0.002 14.7 <0.01
Table 5 : Comparative in vitro cytotoxicity data of benzothiazole and benzoxazle linked PBD hybrids with piperizine and with out piperizine in selected human cancer cell lines (Gl50 values9 in μΜ concentration)
Figure imgf000020_0001
9f <0.01 <0.01 <0.01 <0.01
9g 0.168 <0.01 0.16 0.16
9h 0.13 0.12 0.1 0.12
9i 0.117 <0.01 0.11 <0.01
9j <0.01 <0.01 <0.01 <0.01
9k 0.13 <0.01 0.01 0.11
91 0.125 <0.01 0.11 0.11
DC-81 0.16 — 0.11 0.17
ADR 0.19 13 <0.01 0.16 a 50% Growth inhibition and the values are mean of three determinations, b brest cancer, c ovary cancer, d colon cancer, e prostate cancer, f cervix cancer, 6 lung cancer, h oral cancer, ADR, adriamycin
Figure imgf000021_0001
Figure imgf000022_0001
Table 6. Gl50 values3 (in μΜ) for compounds 9a-j in selected human cancer cell lines.
Comp MCF 7b A 2780c Colo PC 3e SiHa' A 549 HOP 62g KBh
205 d
9a <0.01 0.108 0.1 0.12 0.13 0.13 0.1 0.12
9b <0.01 <0.01 0.09 <0.01 <0.01 0.12 <0.01 <0.01
9c <0.01 0.116 0.13 0.11 0.13 <0.01 0.11 0.11
9e <0.01 0.097 0.12 <0.01 . 0.107 0.105 <0.01 <0.01
9f <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
9g 0.14 0.147 0.1 0.16 0.168 <0.01 0.16 0,16
9i <0.01 0.08 <0.01 <0.01 0.117 <0.01 0.11 <0.01
9j <0.01 <0.01 0.11 <0.01 <0.01 <0.01 <0.01 <0.01
9k <0.01 0.086 0.17 <0.01 0.13 <0.01 0.01 0.11
91 <0.01 0.099 <0.01 <0.01 0.125 <0.01 0.11 0.11
DC-81 0.16 0.13 0.10 -- 0.16 -- 0.11 0.17
Figure imgf000022_0002
a 50% Growth inhibition and the values are mean of three determinations, b brest cancer, c ovary ca ncer, d colon cancer, e prostate cancer, f cervix cancer, g lung cancer, h oral cancer, ADR, adriamycin.
EXAMPLES
The following examples are given by way of illustration and therefore should not be construed to limit the scope of present invention in any way.
EXAMPLE 1
7-Methoxy-8-[3-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl)propyl]oxy(llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9a).
To a solution of ((2S)-[/V-{4-(3-(piperazin-l-yl)propyloxy)-5-methoxy-2-nitro benzoyl] pyrrolidine-2- carboxaldehydediethylthioacetal 4a (535 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 4-[3(benzothiazol-2-yl)bromopropyloxy]phenol 6a (354 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum . The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7a (605 mg, 75%).
H N M R (CDCI3 300 M Hz): δ 8.02 (d, 2H, J = 9.0 Hz), 7.83 (d, 1H, J = 7.5 Hz), 7,61 (s, 1H), 7.42 (m^ 1H, J = 8.3 Hz), 7.31 (d, 2H, J = 7.5 Hz), 6.94 (d, 2H, J = 9.0 Hz), 6.81 (s, 1H ) 4.85 (d, 1H, J = 3.7 Hz), 4.7 (m, 1H), 4.16-4.10 (m, 4H), 3.92 (s, 3H), 3.21-3.34 (m, 2H), 2.63-2.85 (m, 4H), 2.55 (m, 9H), 2.26 (m, 2H), 2.05 (m, 6H, J = 6.04 Hz), 1.82 (m, 2H), 1.2-1.4 (m, 6H, J = 6.79 Hz).
ESI MS: m/z 795 (M+H)+.
To compound 7a (682 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 8a (525 mg, 80%), which was used directly in the next step.
A solution of 8a (652 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase Was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 ' (4%) to give compound 9a (367 mg, 60%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
XH NMR (CDCI3, 300 MHz): δ 8.04 (d, 2H, J - 8.8 Hz), 7.88 (d, 1H, J = 8.0 Hz), 7.68 (d, 1H, J = 4.5 Hz), 7.52 (s, 1H), 7.3-7.45 (m, 3H), 7.01 (d, 2H, J = 8.8 Hz), 6.84 (s, 1H), 4.0-4.12 (m, 2H), 3.92 (s, 3H), 3.82-3.55 (m, 4H), 2.45-2.52 (m, 8H), 2.25- 2.32 (m, 1H), 1.91-2.09 (m, 6H), 1.54-1.88 (m, 4H), 1.28-1.38 (m, 2H).
ESIMS: m/z 640 (M+H)+, 671 (M++MeOH).
EXAMPLE 2
7-Methoxy-8-[3-(4-{4-[3(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]propyl}piperazin-l-yl) propyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [1,4] benzodiazepin-5-one(9b). >
To a solution of (2S)-[N-{4-(3-(piperazin-l-yl)propyloxy)-5-methoxy-2-nitro benzoyl] pyrrolidine-2- carboxaldehyde diethylthioacetal 4a (535 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and 4-[3(benzothiazol-2-yl)bromopropyloxy]3-methoxyphenol 6b (384 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7b (628 mg) 75%.
H NMR (CDCI3, 300 MHz): 5 8.01 (d, 1H, J = 8.3 Hz), 7.89 (d, 1H, J = 8.3 Hz), 7.75 (m, 2H), 7.55 (dd, 1H, J = 7.5 Hz), 7.45 (t, 1H, J = 8.3 Hz), 7.3 (t, 1H, J = 8.0 Hz), 6.93 (d, IH, J = 8.3 Hz), 6.7 (s, 1H), 4.85 (d, 1H, J = 3.7 Hz), 4.65 (m, 1H), 4.2 (m, 4H), 4.00 (s, 3H), 3.92 (s, 3H), 3.21-3.34 (m, 2H), 2.62-2.83 (m, 6H), 2.59- 2.52 (m, 12H), 2.55 (m), 2.25 (m, 2H), 2.13-2.00 (m, 2H), 1.80 (m, 1H), 1.63-1.97 (m, 6H).
ESIMS: m/z 823 (M)\ To compound 7b (712 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S0 and evaporated under vacuum to afford the crude amino diethylthioacetal 8b (514 mg, 75%), which was used directly in the next step.
A solution of 8b (682 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9b (344 mg, 60%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
2H NM (CDCI3, 300 MHz): δ 8.02 (d, 1H, J = 8.3 Hz), 7.88 (d, 1H, J = 7.5 Hz), 7.71 (m, 2H), 7.65 (d, 1H, J = 4.5 Hz), 7.55 (dd, 1H, J = 7.5 Hz), 7.48 (d, 1H, J = 7.5 Hz), 7.36 (m, 1H, J = 6.7 Hz), 6,92 (d, 1H, J = 8.3 Hz), 6.78 (s, 1H), 4.1-4.4 (m, 4H), 4.0 (s, 3H), 3.95 (s, 3H), 3.5-3.85 (m, 3H), 2.38-2.57 (m, 8H), 2.2-.32 (m, 1H), 1.96-2.05 (m, 6H), 1.88-1.67 (m, 2H), 1.21-1.36 (m, 2H).
ESIMS: /T)/z 670 (M+H)+.
EXAMPLE 3
7-Methoxy-8-[3-{4-{4-[3(6-flouro-l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl)propyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9c).
To a solution of (2S)-[N-{4-(3-(piperazin-l-yl)propyloxy)-5-methoxy-2-nitro benzoyl] pyrrolidine-2- carboxaldehyde diethylthioacetal 4a (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 4-[3(6-fluorobenzothiazol-2-yl)bromopropyloxy]3-methoxyphenol 6c (382 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7c (612 mg, 75%).
JH NMR (CDCI3, 300 MHz): δ 7.91-8.02 (m, 3H, J= 8.3, 9.0 Hz), 7.68 (s, 1H), 7.55 (dd, 1H, J = 7.5 Hz), 7.20 (td, 1H, J = 7.55 Hz), 6.95 (d, 2H, J = 8.3 Hz), 6.75 (s, 1H), 4.85 (d, 1H, J = 3.7 Hz), 4.75 (m, 1H), 4.15 (m, 4H), 3.92 (s, 3H), 3.21-3.34 (m, 2H), 2.63-2.85 (m, 4H), 2.55 (m, 12H), 2.25 (m, 2H), 2.05 (m, 5H), 1.6-1.8 (m. 3H), 1.35 (q, 6H, = 6.79 Hz).
ESIMS: m/ 783 (M+H)+.
To compound 7c (696 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethyl thioacetal 8c (535 mg, 80%), which was used directly in the next step. A solution of 8c (666 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S0 ). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (4%) to give compound 9c (350 mg, 60%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
*H NMR (CDCI3, 300 MHz): δ 7.91-8.0 (m, 3H, J= 8.3, 9.0 Hz), 7.64 (d,lH, J= 4.7 Hz), 7.55 (dd, 1H, J = 7.5 Hz), 7.50 (s, 1H), 7.20 (td, 1H, J = 7.5 Hz), 6.95 (d, 2H, J = 8.3 Hz), 6.75 (s, 1H), 4.12 (m, 4H), 3.92 (s, 3H), 3.82-3.52 (m, 3H), 2.55-2.52 (m, 8H), 2.32 (t, 2H), 2.09 (m, 6H), 1.88 (m, 2H), 1.38 (m, 2H).
ESIMS: m/z 658 (M+H)+.
EXAMPLE 4
7-Methoxy-8-[3-(4-{3-[3(l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl)propyl]oxy-(lla5)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9d).
To a solution of (2S)-[N-{4-(3-(piperazin-l-yl)propyloxy)-5-methoxy-2-nitro benzoyl] pyrrolidine-2- carboxaldehyde diethylthioacetal 4a (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous 2C03 (552 mg, 4 mmol) and the 3-[3(benzothiazol-2-yl)bromopropyloxy]phenol 6d (363 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7d (580 mg, 70%).
H NMR (CDCI3): δ 8.03 (d, lH, J = 8.309 Hz), 7.85 (d, 1H, J = 8.309 Hz), 7.69 (d, 1H, J = 1.6 Hz), 7.59 (d, 1H, J = 8.309 ), 7.45 (dt, 1H, J = 7.554 Hz), 7.33 (dt, 1H, J = 8.309 Hz), 6.92 (d, 1H, J = 8.309 Hz), 6.78 (s, 1H), 4.85 (d, 1H, J = 3.77 Hz), 4.65 (m, 1H), 4.25 (m, 4H, J = 6.043 ), 3.92(s, 3H), 3.12 (m, 2H), 2.6-2.8 (m, 4H), 2.28 ( m ), 1.80 (m, 10H), 1.2-1.4 (m, 6H).
ESIMS: m/z 795 (M+H)+.
To compound 7d (726 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum; the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 ml and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethyl thioacetal 8d (559 mg, 80%), which was used directly in the next step.
A solution of 8d (696 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4: 1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9d (320 mg, 55%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
H NM (CDCI3): 8.03 (d, 1H, J = 8.309 Hz), 7.85 (d, 1H, J = 8.309 Hz), 7.69 (d, 1H, J = 4.52 Hz), 7.59 (d, 1H, J = 8.309 ), 7.45 (dt, 1H, J = 7.554 Hz), 7.33 (dt, 1H, J = 8.309 Hz), 6.92 (d, 1H, J = 8.309 Hz), 6.78 (s, 1H), 4.85 (d, lH, J = 3.77 Hz), 4.12 (m), 3.92 (s, 3H), 3.82 (m), 3.71 (m), 3.55 ( m ), 2.52 (m), 2.32 (m),2.09 (t), 1.88 (m), 1.38 (m).
ESIMS: m/z 641 (M+H)+.
EXAMPLE 5
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5W-pyrrolo[2,l-c][l,4jbenzodiazepin-5-one (9e).
To a solution of (2S)-[N-{4-(4-(piperazin-l-yl)butyloxy)-5-methoxy-2-nitro benzoyl]pyrrolidine-2- carboxaldehyde diethylthioacetal 4b (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and 4-[4(benzothiazol-2-yl)bromobutyloxy]phenol 6e (368 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7e (668 mg, 80%).
JH NM R (CDCI3, 300 M Hz): δ 8.05 (d, 2H, J = 9.0 Hz), 7.83 (d, 1H, J = 7.5 Hz), 7.61 (s, 1H), 7.42 (m, 1H, J = 8.3 Hz), 7.31 (m, 2H, J = 7.5 Hz), 6.94 (d, 2H, J = 9.0 Hz), 6.81 (s, 1H), 4.89 (d, 1H, J = 3.7 Hz), 4.65 (m, 1H), 4.17 (m, 4H, J = 6.4 Hz), 3.92 (s, 3H), 3.23 (m, 2H), 2.52-2.8 (m, 14H), 2.27 (m, 2H), 2.31 (m, 2H), 2.12 (m, 2 H), 1.63-1.97 (m, 10H), 1.39 (q, 6H, J = 6.79 Hz).
ESI MS: m/z 823 (M+H)+. To compound 7e (665 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 8e which was used directly in the next step.
A solution of 8e (649 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a ceiite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (4%) to give compound 9e (273 mg, 50%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
JH N R (CDCI3; 300 MHz): δ 8.04 (d, 2H, J = 6.7 Hz), 7.88 (d, 1H, J = 7.5 Hz), 7.68 (d, 1H, J = 4.5 Hz), 7.52 (m, 2H), 7.41-7.48 (m, 2H, J = 8.3 Hz), 7.01 (d, 2H, J = 9.0 Hz), 6.89 (s, 1H), 4.21-4.12 (m, 4H), 3.90 (s, 3H), 3.58-3.8 (m, 3H), 2.52-2.45 (m, 8H), 2.30-2.32 (m, 2H), 1.90-2.04 (m, 2H), 1.7-1.88 (m, 4H), 1.52-1.67 (m, 6H), 1.32-1.34 (m, 2H).
ESIMS: m/ 668 (M+H)+. EXAMPLE 6
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl}piperazin-l-yl)butyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrro|o[2,l-c][l,4]benzodiazepin-5-one (9f).
To a solution of (2S)-[N-{4-(4-(piperazin-l-yl)butyloxy)-5-methoxy72-nitro benzoyl]pyrrolidine-2- carboxaldehyde diethylthioacetal 4b (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 4-[4(benzothiazol-2-yl)bromobutyloxy]3-methoxyphenol 6f (398 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate- hexane (8:2) as eluant to afford pure compound of 7f (649 mg, 75%).
*H NMR (CDCI3, 300 MHz): δ 8.01 (d, 1H, J = 8.3 Hz), 7.75 (m, 2H), 7.63 (s, 1H), 7.52 (dd, 1H, J = 8.0, 1.6 Hz), 7.45-7.3 (d, 2H, J = 8.3 Hz), 6.95 (d, 1H, J = 8.3 Hz), 6.75 (s, 1H), 4.89 (d, 1H, J = 3.7 Hz), 4.65 (m, 1H), 4.71 (m, 4H), 4.02 (s, 3H), 3.94 (s, 3H), 3.23 (m, 2H), 2.6-2.8 (m, 14H), 2.57 (m, 2H J = 6.04 Hz), 2.31 (m, 2H), 2.12 (m, 2H), 1.6-1.97 (m, 10H), 1.35 (q, 6H, J = 7.6 Hz).
ESIMS: m/z 852 (M+H)+. To compound 7f(695 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 8f which was used directly in the next step.
A solution of 8f (679 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI^ (5%) to give compound 9f (281 mg, 50%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
*H NM (CDCI3, 200 MHz): δ 8.02 (d, 1H, J = 8.3 Hz), 7.71-7.86 (d, 3H, J = 7.5 Hz), 7.65 (d, 1H, J = 4.5 Hz), 7.55 (dd, 1H, J = 7.5 Hz), 7.46 (d, 1H, J= 7.5 Hz), 7.36 (m, 1H, J = 6.7 Hz), 6.94 (d, 1H, J = 8.3 Hz), 6.8 (s, lH), 4.22-4.16 (m, 4H, J = 6.0 Hz), 4.01 (s, 3H), 3.92 (s, 3H), 3.55-3.82 (m, 3H), 2.38-2.57 (m, 8H), 2.29- 2.34 (m, 2H), 2.04-2.1 (m, 2H), 1.6-1.86 (m, 4H), 1.53-1.64 (m, 6H), 1.34-1.38 (m," 2H). ESIMS: m/z 698 (M+H)+.
EXAMPLE 7
7-Methoxy-8-[4-(4-{4-[4(6-fluoro-l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9g).
To a solution of 4b (400 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03.(552 mg, 4 mmol) and the 6g (276 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7g (435 mg, 70%). H N R (CDCI3, 300 MHz): δ 7.91-7.98 (m, 3H, J= 8.3, 9.0 Hz), 7.68 (s, 1H), 7.54 (dd, 1H, J = 7.5, 2.2 Hz), 7.18 (d, 1H, J = 7.5 Hz), 6.96 (d, 2H, J = 8.30 Hz), 6.75 (s, 1H) 4.89 (d, 1Ή, J = 3.77 Hz), 4.65 (m, 1H), 4.17 (m, 4H, J = 6.40 Hz), 3.92 (s, 3H), 3.23 (m, 2H), 2.52-2.8 (m, 14H), 2.54 (m, 2H), 2.31 (m, 2H), 2.10 (m, 2H), 1.63-1.97 (m, 10H), 1.39 (q, 6H, J = 6.79 Hz). ESIMS: m/z 841 (M+H)+.
·
To compound 7g (709 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum; the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 8g which was used directly in the next step.
A solution of 8g (679 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9g (344 mg, 60%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
1H NMR (CDCI3, 300 MHz): δ 7.92-8.04 (m, 3H, 8.3, 9.0 Hz), 7.65 (d, 1H, J= 4.3 Hz), 7.54 (dd, 2H, J = 7.5 Hz ), 7.22 (td, 1H, J = 7.5 Hz), 6.96 (d, 2H, J = 8.3 Hz), 6.8 (s, 1H), 4.23-4.12 (m, 4H), 3.90 (s, 3H), 3.55-3.8 (m, 3H), 2.52-2.45 (m, 8H), 2.30-2.32 (m, 4H), 2.12-2.04 (m, 2H), 1.65-1.88 (m, 6H), 1.45-1.35 (m, 2H). ESIMS: m/z 686 (M+H)+.
EXAMPLE 8 .
7-Methoxy-8-[4-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9h).
To a solution of 4b (400 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 6h (268 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7h (456 mg, 75%).
JH NMR (CDCI3): δ 8.03 (d, 1H, J = 8.309 Hz), 7.89 (d, J = 8.309 Hz ), 7.69 (s, 1H), 7.59 (d, 1H, J = 8.309 Hz), 7.45 (m, J = 7.554 Hz),7.35 (m, J = 8.309 Hz), 6.92 (dd, J = 8.309 Hz), 6.78 (s), 4.82 (d, J - 3.77 Hz), 4.65 (m), 4.2 (m, J = 6.04 Hz), 3.92 (s, 3H), 3.23 (m), 2.62-2.83 (m), 2.57 (m, J = 6.043 Hz ), 2.31 (m), 2.12 (m), 1.63-1.97 (m), 1.38 (m, J = 6.798 Hz). ES1MS: m/z 823 (M)+.
To compound 7h (727 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S0 and evaporated under vacuum to afford the crude amino diethylthioacetal 8h, which was used directly in the next step.
A solution of 8h(697 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S0 ). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9h (322mg, 55%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
H NM (CDCI3): 8.03 (d, 1H, J = 8.309 Hz), 7.85 (d, 1H, J = 8.309 Hz), 7.69 (d, 1H, J = 4.532 Hz), 7.59 (d, 1H, J = 8.309 ), 7.45 (dt, 1H, J = 7.554 Hz), 7.33 (dt, 1H, J = 8.309 Hz), 6.92 (d, 1H, J = 8.309 Hz), 6.78 (s, 1H), 4.12 (m/4H), 3.90 (s, 3H), 3.8 (m, 3H), 3.71 (m, 2H), 3.55 (m),2.52 (m), 2.45 (m), 2.32 (m), 2.04 (m), 1.88 (m), 1.67 (m), 1.34 (m). ESIMS: m/z 668 (M+H)+.
EXAMPLE 9
7-Methoxy-8-[3-(4-{4-[3(l,3-benzoxazol-2-yl)-phenoxy]propyl}piperazin-l-yl)propyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5W-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9i).
To a solution of (2S)-[N-{4-(3-(piperazin-l-yl)propyloxy)-5-methoxy-2-nitro benzoyl] pyrrolidine-2- carboxaldehyde diethylthioacetal 4a (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 4-[3(benzoxazol-2-yl)bromopropyloxy]phenol 6i (346 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (8:2) as eluant to afford pure compound of 7i (631 mg, 75%).
XH NMR (CDCI3, 300 MHz): δ 7.85 (d, 1H, J = 7.5 Hz), 778 (m, 1H, J = 9.0 Hz), 7.71 (m, 2H), 7.57 (m, 1H, J = 8.3 Hz), 7.45 (t, 1H, J = 7.4 Hz), 7.38 (t, 1H, J = 9.0 Hz), 7.01 (d, 2H, J = 7.5 Hz), 6.82 (s, 1H), 4.86 (d, 1H, J = 3.7 Hz), 4.73 (m, 1H), 4.18 (m, 4H, J = 6.0 Hz), 3.94 (s, 3H), 3.29 (m, 2H), 2.54-2.83 (m, 14H), 2.27 (m, 2H), 2.13-1.73 (m, 12H), 1.36 (t, 6H, J = 6.79 Hz). ESIMS: m/z 778 (M+H)+.
To compound 7i (695 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% Na HC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S0 and evaporated under vacuum to afford the crude amino diethylthioacetal 8i which was used directly in the next step.
A solution of 8i (679 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C forl2 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9i (334 mg, 55%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
H NMR (CDCI3, 300 MHz): δ 8.2 (d, 2H, J = 8.3 Hz), 7.86 (d, 1H, J = 7.5 Hz), 7-65 (d, 1H, J = 4.5 Hz), 7.55 (dd, 2H, J = 7.5 Hz), 7.48 (d, 1H), 7.36 (m, 1H, J = 6.7 Hz), 6.92 (d, 2H, J = 8.3 Hz), 6.78 (s, 1H), 4.19-4.13 (m, 4H, J = 6.0 Hz), 3.92 (s, 3H), 3.54-3.82 (m, 4H), 2.38-2.57 (m, 8H), 2.32 (m, 2H), 2.04-2.15 (m, 4H), 1.67-1.88 (m, 8H) 1.30-1.38 (m, 2H). ESIMS: m/z 698 (M+H)+.
EXAMPLE 10
7-Methoxy-8-[3-(4-{4-[3(l,3-benzoxazol-2-yl)-2-methoxyphenoxy]propyl}piperazin-l-yl)propyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9j).
To a solution of (2S)-[N-{4-(3-(piperazin-l-yl)propyl)-5-methoxy-2-nitrobenzoyl] pyrrolidine-2- carboxaldehyde diethylthioacetal 4a (535 mg, 1 mmol) in acetone ( 10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and 4-[3(benzoxazol-2-yl)bromopropaxy]3-methoxyphenol 6j (384 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (7:2) as eluant to afford pure compound of 7j (616 mg) 75%. H NM R (CDCI3, 300 MHz): δ 7.85 (d, 1 J = 8.3 Hz), 7.78 (d, 1H, J = 8.3 Hz), 7.71 (s, 1H) 7.57 (m, 2H, J = 9.0 Hz), 7.36 (dd, 2H, J = 9.0 Hz), 6.93 (d, 1H, J = 8.3 Hz), 6.82 (s, 1H), 4.85 (d, 1H, = 3.7 Hz), 4.71 (m, 1H)» 4.19 (m, 4H, J = 6.0 Hz), 4.04 (s, 3H), 3.92 (s, 3H), 3.26 (m, 2H), 2.71-2.43 (m, 16H), 2.28 (m, 2H), 2.05 (m), 1.63-2.14 (m, 8H), 1.38 (t, 6H). ESI MS: m/z 809 (M+H)+.
To compound 7j(712 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 8j (511 mg, 75%), which was used directly in the next step.
A solution of 8j (682 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4: 1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give' compound 9j (320 mg, 56%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
• :H NM R (CDCI3, 200 M Hz): δ 7.85 (d, 1H, J = 8.3 Hz), 7.78 (d, 1H, J = 7.5 Hz), 7.71 (m, 2 H), 7.65 (d, 1H, J = 4.5 Hz), 7.51 (dd, 1H, j = 7.5 Hz), 7.38 (m, 1H, J = 7.5 Hz), 7.36 (m, 1H, J = 6.7 Hz), 6.92 (d, J = 8.3 Hz), 6.78 (s, 1H), 4.1-4.4 (m, 4H), 4.04 (s, 3H), 3.9 (s, 3H), 3.5-3.85 (m, 4H), 2.38-2.57 (m, 8H), 2.32 (t, 2H), 2.05 (t, 2H), 1.88-1.66 (m, 4H), 1.38 (m, 2H). ESIMS: m/z 654 (M+H)+. .
EXAMPLE 11
7-Methoxy-8-[3-(4-{3-[3(l,3-benzoxazol-2-yl)-phenoxy]propyl}piperazin-l-yl)propyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9k).
To a solution of (2S)-[N-{4-(3-(piperazin-l-yl)propyl)-5-methoxy-2-nitrobenzoyl] pyrrolidine-2- carboxaldehyde diethylthioacetal 4a (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 3-[3(benzoxazol-2-yl)bromopropaxy]phenol 6k (346 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (7:2) as eluant to afford pure compound of 7k (568 mg, 70%).
H NMR (CDC!3): δ 7.85 (d, 1H, J = 7.654 Hz), 7.78 (d, 1H, J = 8.309 Hz), 7.71 (d, 1H, J = 1.6 Hz), 7.57 (d, 1H, J = 8.309 ), 7.45 (dt, 1H, J = 7.554 Hz), 7.38 (dt, 1H, J = 8.309 Hz), 7.01 (d, 1H, J = 8.309 Hz), 6.82 (s, 1H), 4.85 (d, 1H, J = 3.77 Hz), 4.7 (m, 1H), 4.20 (m, 4H, J = 6.043 ), 3.92 (s, 3H), 3.36 (m, 2H), 2.6-2.8 (m, 4H), 2.49 (m), 1.80 (m, 10H), 1.2-1.4 (m, 6H). ESI S: m/z 778 (M+H)+.
To compound 7k (726 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum; the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethyl thioacetal 8k (557 mg, 80%), which was used directly in the next step.
A solution of 8k (696 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S0 ). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9k (368 mg, 55%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
H NMR (CDCI3): 7.85 (d, 1H, J = 8.309 Hz), 7.78 (d, 1H, J = 8.309 Hz), 7.65 (d, 1H, J = 4.52 Hz), 7.59 (d, 1H, J = 8.309 ), 7.45 (dt, 1H, J = 7.554 Hz), 7.33 (dt, 1H, J = 8.309 Hz), 6.92 (d, 1H, J = 8.309 Hz), 6.78 (s, 1H), 4.85 (d, 1H, J = 3.77 Hz), 4.12 (m), 3.92 (s, 3H), 3.82 (m), 3.71 (m), 3.55 ( m ), 2.52 (m), 2.32 (m),2.09 (t), 1.88 (m), 1.38 (m). ESIMS: m/z 624 (M+H)+. EXAMPLE 12
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (91).
To a solution of (25)-[N-{4-(4-(piperazin-l-yl)butyloxy)-5-methoxy-2-nitro benzoyl]pyrrolidine-2- carboxaldehyde diethylthioacetal 4b (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and 4-[4(benzoxazol-2-yl)bromobutyl]phenol 61 (351 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (7:3) as eluant to afford pure compound of 71 (655 mg, 80%).
H NM (CDCI3, 300 MHz): δ 7.85 (d, 2H, J = 7.6 Hz), 7.78 (d, 1H, J = 9.0 Hz), 7.71 (s, 1H), 7.57 (m, 1H, J = 8.3 Hz), 7.45 (m, 2H, J = 7.5Hz), 7.01 (d, 2H, J = 7.5 Hz), 6.81 (s, 1H), 4.89 (d, 1H, J = 3.7 Hz), 4.65 (m, 1H), 4.16 (m, 4H, J = 6.4 Hz), 3.92 (s, 3H), 3.23 (m, 2H), 2.52-2.8 (m, 14H), 2.31 (m, 2H), 2.12 (m, 2H), 1.63- 1.97 (m, lOH), 1.39 (q, 6H, J = 6.79 Hz). ESIMS: m/z 807 (M+H)+.
To compound 71 (665 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 81 which was used directly in the next step.
A solution of 81 (649 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) . and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (4%) to give compound 91 (299 mg, 55%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
XH NMR (CDCI3, 300 MHz): δ 7.85 (d, 1H, J = 6.7 Hz), 7.81 (d, 1H, J = 7.5 Hz), 7.76 (d, 1H, J = 4.54 Hz), 7.72 (m, 1H), 7.68 (d, 1H, J = 4.5 Hz), 7.52-7.58 (m, 2H, J = 9.06 Hz), 7.50 (s, 1H), 7.38 (td, 1H), 7.02 (d, 1H), 6.8 (s, 1H), 4.05-4.1 (m, 4H), 3.90 (s, 3H), 3.51-3.8 (m, 4H), 2.52-2.45 (m, 8H), 2.32 (m, 2H), 2.04 (m, 6H), 1.88-1.6 (m, 4H), 1.34 (m, 2H). ESIMS: m/z 653 (M+H)+. EXAMPLE 13
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl}piperazin-l-yl)butyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9m).
To a solution of (2S)-[/V-{4-(4-(piperazin-l-yl)butyl)-5-methoxy-2-nitrobenzoyl] pyrrplidine-2- carboxaldehyde diethylthioacetal 4b (549 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 4-[4(benzoxazol-2-yl)bromobutyl]3-methoxyphenol 6m (382 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (7:1) as eluant to afford pure compound of 7m (637 mg, 75%).
aH NMR (CDCI3, 300 MHz): δ 7.75-7.89 (m, 3H, J = 8.30 Hz), 7.71 (s, 1H), 7.52 (m, 1H), 7.36 (m, 1H, J = 9.0 Hz), 7.01 (d, 2H, J = 8.3 Hz), 6.82 (s, 1H), 4.89 (d, 1H, J = 3.7 Hz), 4.65 (m, 1H), 4.71 (m, 4H), 4.02 (s, 3H), 3.94 (s, 3H), 3.23 (m, 2H), 2.6-2.8 (m, 14H), 2.57 (m, 2H, J = 6.04 Hz), 2.31 (m, 2H), 2.12 (m, 2H), 1.6-1.97 (m, 10H), 1.35 (q, 6H, J = 7.6 Hz). ESIMS: m/z 837(M+H)+.
To compound 7m (695 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S0 and evaporated under vacuum to afford the crude amino diethylthioacetal 8m, which was used directly in the next step.
A solution of 8m (679 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 mL) and the combined organic phase was dried (Na2S04). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9m (287 mg, 50%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the imine form.
XH NMR (CDCI3, 300 MHz): δ 7.85 (d, 1H, J = 8.3 Hz), 7.76 (d, 1H, 7 = 7.5 Hz), 7.71 (d, 1H), 7.68 (d, 1H, J = 4.5 Hz), 7.36 (dd, 1H, J = 7.5 Hz), 7.05-7.01 (m, 2H, J = 6.7 Hz), 6.92 (d, 2H, J = 8.3 Hz), 6.79 (s, 1H), 4.21- 4.15 (m, 4H, J = 6.0 Hz), 4.01 (s, 3H), 3.92 (s, 3H), 3.54-3.82 (m, 3H), 2.38-2.57 (m, 8H), 2.34 (m, 2H), 2.12-2.04 (m, 6H), 1.52-1.88 (m, 6H), 1.36-1.38 (m, 2H). ESIMS: m/z 683 (M+H)+. EXAMPLE 14
7-Methoxy-8-[4-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)- l^^jlla-tetrahydro-SH-pyrrololZjl-cltl^lbenzodiazepin-S-oneigm).
To a solution of 4b (400 mg, 1 mmol) in acetone (10 mL) was added anhydrous K2C03 (552 mg, 4 mmol) and the 6n (256 mg, 1 mmol). The reaction mixture was heated to reflux for 48 h. After completion of the reaction as indicated by TLC, potassium carbonate was removed by suction filtration and the solvent was removed under vacuum. The crude product thus obtained was purified by column chromatography using ethylacetate-hexane (7:2.) as eluant to afford pure compound of 7n (447 mg, 75%). H NM (CDCI3): δ 7.85 (d,' lH, J = 8.309 Hz), 7.78 (d, J = 8.309 Hz ), 7.71 (s, 1H), 7.59 (d, 1H, J = 8.309 Hz), 7.53 (m, J = 7.554 Hz), 7.45(m, J = 8.309 Hz),7.38 (m), 7.01 (d 2H) 6 (s, 1H), 4.82 (d, J = 3.77 Hz), 4.65 (m), 4.2 (m, J = 6.04 Hz), 3.92 (s, 3H), 3.23 (m), 2.62-2.83 (m), 2.57 (m, J = 6.043 Hz ), 2.31 (m), 2.12 (m), 1.63- 1.97 (m), 1.38 (m, J = 6.798 Hz). ESIMS: m/z 807 (M)+.
To compound 7n (727 mg, 1 mmol) in methanol (20 mL) was added SnCI2.2H20 (1.125 g, 5 mmol) and refluxed at 80 °C for 5 h or until the TLC indicated that reaction was completed. The methanol was evaporated under vacuum, the aqueous layer was then carefully adjusted to pH 8 with 10% NaHC03 solution and then extracted with ethyl acetate and chloroform (2x30 mL and 2x30 mL). The combined organic phase was dried over Na2S04 and evaporated under vacuum to afford the crude amino diethylthioacetal 8n, which was used directly in the next step.
A solution of 8n(697 mg, 1 mmol), HgCI2 (613 mg, 2.26 mmol) and CaC03 (246 mg, 2.46 mmol) in acetonitrile-water (4:1) was stirred slowly at 27 °C for 12 h. The reaction mixture was diluted with ethyl acetate (30 mL) filtered through a celite pad. The clear organic supernatant was extracted with saturated 5% NaHC03 (20 mL), brine (20 m L) and the combined organic phase was dried ( Na2S0 ). The organic layer was evaporated under vacuum and purified by column chromatography using MeOH-CHCI3 (5%) to give compound 9n (315 mg, 55%). This material was repeatedly evaporated from CHCI3 in vacuum to generate the irriine form.
H N M R (CDCI3): 7.85 (d, 1H, J = 8.309 Hz), 7.75 (d, 1H, J = 8.309 Hz), 7.69 (d, 1H, J = 1.6 Hz), 7.59 (d, 1H, J = 8.309 ), 7.45 (dt, 1H, J = 7.554 Hz), 7.33 (dt, 1H, J = 8.309 Hz), 6.92 (d, 1H, J = 8.309 Hz), 6.78 (s, 1H), 4.12 (m, 4H), 3.90 (s, 3H), 3.8 (m, 3H), 3.71 (m, 2H), 3.55 (m),2.52 (m), 2.45 (m), 2.32 (m), 2.04 (m), 1.88 (m), 1.67 (m), 1.34 (m). ESIMS: m/z 652 (M+H)+.
BIOLOGLCAL ACTIVITY
DNA binding affinity of novel benzothiazole, benzoxazole linked PBD hybrids (9a-h)
Compounds have been subjected to thermal denaturation studies with duplex-form calf thymus DNA (CT-DNA) using an modification of a reported procedure (Newman, M. S. Carcinog-compr. Surv. 1976, 1, 203; (b) Hecht, S. S..; Loy, M.; Hoffman, Carcinog-compr. Surv. 1976, 1, 325). . Working solutions in aqueous buffer (10 mM NaH2P04/Na2H P04, 1 rtiM Na2EDTA, pH 7.00 + 0.01) containing CT-DNA (100 μητ in phosphate) and the PBD (20 μηι) have been prepared by addition of concentrated PBD solutions in DMSO to obtain a fixed [PBD]/[DNA] molar ratio of 1:5. The DNA-PBD solutions have been incubated at 37 °C for 0 and 18 h prior to analysis. Samples have been monitored at 260 nm using a Beckman DU-800 spectrophotometer fitted with high performance temperature controller, and heated at 1 °C min_1 in the 40-110 °C range. DNA heii — coil transition temperatures (Tm) have been obtained from the maxima in the d(/A26o)/d 7" derivative plots. Drug-induced alterations in DNA melting behavior are given by: Tm = 7~ m(DNA + PBD) - 7" m(DNA alone), where the Tm value for the PBD-free CT-DNA is 69.1 ± 0.01. The fixed [PBD]/[DNA] ratio used has not resulted in binding saturation of the host DNA duplex for any compound examined.
The DNA binding activity for these novel C8-linked benzothiazole, benzoxazole-PBD hybrids has been examined by thermal denaturation studies using calf thymus (CT) DNA. Melting studies show that these compounds stabilize the thermal helix— > coil or melting stabilization (ATm) for the CT-DNA duplex at pH 7.0, incubated at 37 °C, where PBD/DNA molar ratio is 1:5. The data for the compounds 9a-n is included in Table 7 for comparison.
Table 7. Thermal denaturation data for benzothiazole and benzoxazle linked PBD hybrids with ca lf thymus (CT) DNA
[PBD]:[DNA] (A7" m°C)a after incubation at 37 °C for
PBD hybrids molar ratio O h 18 h
9a 1:5 10.2 10.8
9b 1:5 12.1 12.7
9c 1:5 10.3 10.7
9d 1:5 11.2 11.5
9e 1:5 12.2 12.6
9f 1:5 15.5 15.9
9g 1:5 12.3 12.6
9h 1:5 11.9 12.3
9i 1:5 9.5 9.7
9j 1:5 10.1 10.3
9k 1:5 9.7 10.2
91 1:5 11.5 11.8
9m 1:5 12.1 12.5
9n 1:5 10.3 10.6
DC-81 1:5 0.3 0.7 a For CT-DNA alone at pH 7.00 ± 0.01, Tm = 69.1 °C ± 0.01 (mean value from 10 separate determinations), all ATm values are ± 0.1 - 0.2 °C. b For a 1:5 molar ratio of [PBD]/[DNA], where CT-DNA concentration^ 100 μΜ and ligand concentration = 20 μΜ in aqueous sodium phosphate buffer [10 mM sodium phosphate + 1 mM EDTA, pH 7.00 ± 0.01].
Anticancer activity: In vitro biological activity studies were carried out at the Advance Center for Treatment Research & Education in Cancer (ACTREC), Navi Mumbai.
The compounds were evaluated for in vitro anticancer activity against eight tumour cells lines derived from seven cancer types (non-small-cell lung, colon, oral, cervix, ovarian, prostate, and breast cancer) as shown in Table 2. For each compound, dose response curves for each cell line were measured at a minimum pf five concentrations at 10 fold dilutions. A protocol of 48 h continuous drug exposure was used and a sulforhodamine B (SRB) protein assay was used to estimate cell viability or growth. The concentration causing 50% cell growth inhibition (GI50) and 50% cell death (LC50, -50% growth) compared with the control was calculated. Compounds 9a-9l have been evaluated for their in vitro cytotoxicity in eight cell lines from seven human cancer types of lung (Hop-62, A-549) colon (COLO-205) cervix (Si-Ha), ovary (A-2780), prostate (PC3) breast (MCF7), oral (KB). The results are expressed as percent of cell growth determined relative to that of untreated control cells (Table-8 and table-9).
Table 8 Gl50 (concentration in μ ) values for the representative compounds 9a-l against human tumour cell lines.
Figure imgf000039_0001
Table 9 LC50 (concentration in μΜ) values for the representative compounds 9a-l against human tumour cell lines. Cell Type 9a 9b 9c 9d 9e 9f 9g 9h 9i 9j 9k 91
LCso LCso LCso LCso LCso LCso LCso LCso LCso LCso LCso LCso
MCF 7 1.9 <0.01 0.17 2.1 0.15 <0.01 2.4 2.2 0.15 <0.01 2.6 0.16
A 2780 23 0.12 2.3 2.4 2.2 0.089 2.25 2,3 2.25 0.139 2.16 2.1
Colo 205 >102 >102 >102 >102 >102 >102 >102 >102 >102 >102 >102 >102
Pc 3 28 2.4 2.3 28 2.5 2.4 31 2.4 0.23 2.5 26 2.1
SiHa 27.5 2.4 27 26 27.8 2.5 0.311 27 28.5 28 27.8 28
A 549 >102 >102 33 >102 >102 >102 >102 >102 >102 >102 >102 30
HOP 62 27 28 29 27 27 2.4 >102 27 27 2.3 25 2.5
KB 2.4 2.2 26 2.3 2.3 0.18 >102 0.2 28 0.2 26 2
The compounds prepared in this invention have shown remarkable cytotixic activity against cancer cell lines. 9a exhibit Gl50 ranging from 0.13 to <0.01 μ . 9b exhibit GI50 ranging from 0.12 to Ο.ΟΙμΜ, 9c exhibit GI50 ranging from 0.13to Ο.ΟΙμΜ, 9d exhibit GI50 ranging from 0.12 to <0.01μΜ; 9e exhibit GI50 ranging from 0.12 to <0.01μΜ, 9f exhibit GI50 <0.01μΜ, 9g exhibit GI50 ranging from 0.168 to Ο.ΟΙμΜ, 9h exhibit GI50 ranging from 0.16 to <0.1μΜ, 9i exhibit GI50 ranging from 0.117 to <0.01μΜ, 9j exhibit GI50 ranging from 0.11 to <0.01μΜ, 9k exhibit GI50 ranging from 0.17 to <0.01μΜ, 91 exhibit GI50 ranging from 0.125 to <0.01μΜ respectively.
ADVANTAGES OF THE INVENTION
A series of benzothiazole/benzoxazole-pyrrolobenzodiazepine conjugates has been prepared and evaluated for anti cancer activity. Compounds 9a-l exhibited potent anticancer activity against various cancer cell lines indicating that these compounds had the potential for its development as broad spectrum anticancer agents. The thermal denaturation studies showed that these conjugates have better DNA binding ability when compared to DC-81.
The structural variation of benzothiazole/benzoxazole with piperazine moiety has been utilized for DNA binding aspect. Moreover, one of the potent conjugate 9f (IICT-302) of this series has been evaluate for its in vivo efficacy studies against MCF-7 (breast cancer) and PC-3 (prostate cancer) by using Adriamycin as positive control. The in vivo efficacy study of 9f has exhibited less toxicity and good RTV then control adriyamycin indicating the potential use of these molecules in treating cancer.

Claims

We claim:
1. Pyrrolo[2,l-c][l,4] benzodiazepine-benzothiazoie or benzoxazole conjugates linked through piperazin moiet of general formula 9
Figure imgf000041_0001
GENERAL FORMULA 9
wherein
, Ri = H, F, OCF3, CF3, CI, OMe;
R2 = OCH3 or H; X = S or O.
Pyrrolo[2,l-c][l,4j benzodiazepine-benzothiazoie or benzoxazole conjugates linked through piperazine moiety of general formula 9 as claimed in claim 1, wherein chemical formula of the representative compounds of general formula 9 are:
7-Methoxy-8-[3-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyl] oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9a);
7-Methoxy-8-[3-(4-{4-[3(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]propyl} piperazin-1- yl)propyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4j benzodiazepin-5-one (9b); 7-Methoxy-8-[3-(4-{4-[3(6-flouro-l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l- yl)propyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9c); 7-Methoxy-8-[3-(4-{3-[3(l,3-benzothiazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyljbxy- (llaS)-l,2,3,lla-tetrahydro-5H-'pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9d);
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl)oxy-(llaS)- l,2,3,lla-tetrahydro-5/-/-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9e);
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-1- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9f);
7-Methoxy-8-[4-(4-{4-[4(6-fluoro-l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy- (llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2/l-c][l,4]benzodiazepin-5-one (9g);
7- ethoxy-8-[4-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl]oxy-(lla5)- l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4]benzodiazepin-5-one (9h). 7-Methoxy-8-[3-(4-{4-[3(l,3-benzoxazol-2-yl)-phenoxy]propyl}piperazin-l-yl) propyl]oxy-(llaS) l,2,3,Ha-tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9i);
7-Methoxy-8-[3-(4-{4-[3(l,3-benzoxazol-2-yl)-2-methoxyphenoxy]propyl} piperazin-1 yl)propyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (9j);
7-Methoxy-8-[3-(4-{3-[3(l,3-benzoxazol-2-yl)-ph'enoxy]propyl}piperazin-l-yl) propyl]oxy-(llaS) l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4]benzodiazepin-5-one (9k);
7-Methoxy-8-[4-(4-{4-[4( li3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl) butyl]oxy-(llaS) l,2,3/lla-tetrahydro-5H-pyrrolo[2,l-c] [l,4] benzodiazepin-5-one (91);
7-Methoxy-8-[4-(4-{4-[4(l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-1 yl)butyl]oxy-(lla5)-l,2;3;lla-tetrahydro-5H-pyrrolo[2,l-c][l/4] benzodiazepin-5-one (9m);
7-Methoxy-8-[4-(4-{4-[3(l,3-benzothiazol-2-yl)-phenoxy] butyl}piperazin-l-yI) butyl]oxy-(llaS) l,2,3,lla-tetrahydro-5/-/-pyrrplo[2l-c][l,4]benzodiazepin-5-one(9n);
7-Methoxy-8-.[4-(4-{3-[4(l,3-benzothiazoi-2-yl)-4-methoxyphenoxy]butyl} piperazin-1 yl)butyl]oxy-(llaS)-l,2/3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4] benzodiazepin-5-one (9o);
7-Methoxy-8-[4-(4-{4-[4(6-trifluoromethyl-l,3-benzothiazol-2-y!)-2- methoxyphenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5/-/-pyrrolo[2,l- c][l,4] benzodiazepin-5-one (9p);
7-Methoxy-8-[4-(4-{4-[4(6-trifluoromethoxy-l,3-benzothiazol-2-yl)-2-methoxy
phenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5/-/-pyrrolo[2;l- c][l,4]benzodiazepin-5-one (9q);
7-Methoxy-8-[4-(4-{4-[4(6-methoxy-l,3-benzothiazol-2-yl)-2-methoxyphenoxy] butyl}piperazin l-yl)butyl]oxy-(lla5)-l;2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4] benzodiazepin-5-one (9r); 7-Methoxy-8-[4-(4-{4-[4(5-fluoro-l,3-benzothiazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-1 yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4] benzodiazepin-5-one (9s);
7-Methoxy-8-[4-(4-{4-[4(6-chloro-l,3-benzothiazol-2-yl)-2-methoxyphenoxy] butyl}piperazin-l yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5W-pyrrolo[2,l-c][l,4] benzodiazepin-5-one (9t);
7-Methoxy-8-[4-(4-{4-[4(5-fluoro-l,3-benzothiazol-2-yl)-phenoxy]butyl}piperazin-l-yl)butyl]oxy- (llaSJ-l^^ la-tetrahydro-SH-pyrrolo^l-cKl^Jbenzodiazepin-S-one (9u);
7-Methoxy-8-[4-(4-{4-[4(6-methoxy-l,3-benzoxazol-2-yl)-2-methoxyphenoxy] butyl}piperazin-l- yl)butyl]oxy-(llaS)-l,2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l;4] benzodiazepin-5-one (9v); 7-Methoxy-8-[4-(4-{4-[4(6-trifluoromethoxy-l,3-benzoxazol-2-yl)-2- methoxyphenoxy]butyl}piperazin-l-yl)butyl]oxy-(llaS)-l,2 illa-tetrahydro-5H-pyrr0lo[2,l- c][l,4]benzodiazepin-5-one (9w);
7-Methoxy-8-[4-(4-{4-[4(6-fluoro-l,3-benzoxazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-1- yl)butyl]oxy-(llaS)-l,2,3;lla-tetrahydro-5H-pyrrolo[2,l-c][l,4] benzodiazepin-5-one (9x);
7-Methoxy-8-[4-(4-{4-[4(5-fluoro-l 3-benzoxazol-2-yl)-2-methoxyphenoxy]butyl} piperazin-1- yl)butyl]oxy-(llaS)-l,
2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l/4] benzodiazepin-5-one (9y);
7-Methoxy-8-[4-(4-{4-[4(6-chioro-l,3-benzoxazol-2-yl)-2-methoxyphenoxy]bijtyl} piperazin-1- yl)butyl]oxy-(llaS)-l;2,3,lla-tetrahydro-5H-pyrrolo[2,l-c][l,4] benzodiazepin-5-one (9z).
3. Pyrrolo[2,l-c][l,4] benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperazine moiety of general formula 9 as claimed in claim 1, wherein structural formula of the
Figure imgf000043_0001
PCT/IN2011/000181
Figure imgf000044_0001
Figure imgf000045_0001
Figure imgf000045_0002
Figure imgf000045_0003
)
Figure imgf000046_0001
4. Pyrrolo[2,l-c] [l,4] benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperazine moiety of general formula 9 as claimed in claim 1, wherein said compounds are useful as anticancer agent.
5. The compound as claimed in claim 1, wherein said compounds exhibiting in-vitro anticancer activity against human cancer cell lines derived from nine cancer types of leukemia cancer cell line, non-small-cell lung cancer cell line, colon cancer cell line, CNS cancer cell line, melanoma cancer cell line, ovarian cancer cell line, prostate cancer cell line, and breast cancer cell line.
6. The com pounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro in- vitro activity against breast (MCF-7) cancer cell line for Gl50 and LC50 are in the ra nge of <0.01 to 0.14μηΊ and <0.01 to 2.6μηι respectively at an exposure period of at least 48 hrs.
7. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro in- vitro activity against ovarian (A 2780) cancer cell line for Gl50 and LC50 are in the range of <0.01 to 0.147μπι and 0.089 to 23 μηα respectively at an exposure period of at least 48 hrs.
8. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro in- vitro activity against colon (Colo205) cancer cell line for Gl50 and LC50 are in the range of <0.01 to 0.17 μηι and >102μιη respectively at an exposure period of at least 48 hrs.
9. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro iri- vitro activity against prostate (PC 3) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to Ο.ΐβμηι and 0.23 to 31μιη respectively at an exposure period of at least 48 hrs.
10. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro ih- vitro activity against cervix (SiHa) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.168 μιτί and 0.311 to 28.5 μηι respectively at an exposure period of at least 48 hrs.
11. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro in- vitro activity against non small cell lung (A549) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to 0.13μιη and 30 to >102 μηη respectively at an exposure period of at least 48 hrs.
12. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro in- vitro activity against non small cell lung (HOP62) cancer cell line for Gl50 and LC 50 are in the range of <0.01 to Ο.ΐβμηι and 2.3 to >102 μιη respectively at an exposure period of at least 48 hrs.
13. The compounds 9a-l as claimed in claim 2, wherein concentration of the compound used fro in- vitro activity against oral (KB) < cancer cell line for Gl50 and. LC50 are in the range of <0.01 to 0.16μιη and 0.18 to >102 μιτι respectively at an exposure period of at least 48 hrs.
14. A process for the preparation of pyrrolo[2,l-c] [l,4]benzodiazepine-benzothiazole or benzoxazole conjugates linked through piperzine of general formula 9 and the said process comprising the steps of :
d.
Figure imgf000047_0001
4a-b
4a (n=3) 4b (n=4)
with benzothiazole or benzoxazole derivative selected from the compound of formula 6a -z
Figure imgf000048_0001
6 a, b, c, e, f, g, I, j, I, m, p-z 6 d, h, k, n, o
in the presence of K2C03, in acetone solvent, under refluxing temperature in the range of 70-75 °C to obtain the resultant nitro compound of formula 7a-z;
Figure imgf000048_0002
e. reducing the above said nitro compound of formula 7a-z as obtained in step (a) with SnCI2.2H20 in methanol solvent, under reflux temperature in the range of 80-85 °C and isolating the corresponding amino compound of formula 8a-z;
f
Figure imgf000048_0003
step (b) with a deprotecting agent etanethiol/BF3.OEt2 by known method to obtain the desired compound of formula 9.
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