AU2011202304A1 - Process for synthesis of dialkoxyorganoboranes - Google Patents

Abstract

Process for synthesis of dial koxyorga noboranes Abstract 5 The invention relates to a process for the synthesis of dialkoxyorganoboranes, in par ticular to a process for the synthesis of dialkoxyorganoboranes by an ester exchange reaction. Moreover, the invention relates to a process for the synthesis of organo oxazaborolidine catalysts (organo-CBS) and of trialkylboroxins. Furthermore, the inven tion relates to methods of using dialkoxyorganoboranes for the preparation of organo 10 CBS catalysts and in Suzuki-type coupling reactions.

Description

pool Section 29 Regulation 3.2(2) AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Application Number: Lodged: Invention Title: Process for synthesis of dialkoxyorganoboranes The following statement is a full description of this invention, including the best method of performing it known to us: P1 11AHAU/0710 I Process for synthesis of dialkoxyorganoboranes Field of the Invention 5 The invention relates to processes for the synthesis of organo-oxazaborolidine catalysts (organo-CBS) and of trialkylboroxins. Moreover, the invention relates to a process for the synthesis of dialkoxyorganoboranes, in particular to a process for the synthesis of dialkoxyorganoboranes by an ester exchange reaction. Furthermore, the invention relates to methods of using dialkoxyorganoboranes for the preparation of organo- CBS catalysts 10 and in Suzuki-type coupling reactions. Background of the Invention Dialkoxyorganoboranes are versatile reagents for organic syntheses and have for exam 15 ple been employed in so diverse fields as in the synthesis of antibiotics, insecticides and organoborohydrides. Dialkoxymethylboranes can potentially be used for the synthesis of methyl-substituted chiral oxazaborolidines (known as MeCBS named after Corey, Bakshi and Shibata. c.f. Corey, E.J. et al., Angew. Chem. Int. Ed., 37, 1986-2012 (1998)), which are powerful enantioselective catalysts for ketone reductions. Another potential use for 20 dialkoxyorganoboranes is in Suzuki-type coupling reactions to introduce an organo group into a molecule under formation of a new C-C-bond (Miyaura, N.; Suzuki, A., Chem Rev. 95, 2457-2483 (1995)). US 5,463,131 describes the preparation of dialkoxyalkylboranes by reacting excess trial 25 kyborates with diborane in the presence of an olefin, e.g.: 4 B(OR)3 + B2H 6 + 6 C 2 H4 ----- 6 Et-B(OR) 2 (R is alkyl) Of course, dialkoxymethylboranes cannot be prepared by that method. 30 Another method for the manufacture of dialkoxyalkylboranes comprises esterification of alkylboronic acids (Brown, H.C. et al., Organometallics 2(10), 1311-1316 (1983), Brown, H.C. et al., Organometallics 2(10), 1316-1319 (1983)) or trialkylboroxins (Dahlhoff, W.V. et al., Liebigs Ann. Chem. 8, 807-810 (1990)) with an appropriate alcohol. 35

R-B(OH)

2 + 2 R'OH ---- +4 R-B(OR') 2 + 2 H20

(R-BO)

3 + 6 R'OH ----- 3 R-B(OR') 2 + 3 H 2 0 (R, R' is alkyl) 40 Water is generated in these reactions, which very often disturbs further application of the product, even if only traces of water remain.

2 Water is especially detrimental to the function of the alkyl-CBS catalysts, which can be prepared from dialkoxyalkylboranes. For this reason Corey proposed the use of bis(trifluoroethoxy)alkylboranes for the synthesis of ethyl- and n-butyl-CBS derivatives to 5 avoid the formation of water as a by-product (Corey, E.J. et al., Tetrahedron Lett. 33(29), 4141-4144 (1992)). The use of bis(dialkylamino)alkylboranes for the synthesis of alkyl CBS catalysts has also been described (Chavant, P.Y, et al., J. Organomet. Chem. 455, 37-46 (1993), but these are quite expensive reagents. 10 It was one object of the present invention to provide a simple and efficient process for the preparation of dialkoxyorganoboranes. The formation of water or other by-products, that might be difficult to handle or to remove, should be avoided during the process. It was another object of the present invention to establish a process for the production of organo-oxazaborolidine catalysts (organo-CBS) using dialkoxyorganoboranes. In 15 addition, a new and efficient method for the preparation of trialkoxyboroxins should be developed. Summary of the Invention 20 Accordingly, the present invention provides a novel process for the preparation of dialkoxyorganoboranes of the formula RI-B(OR 2

)

2 , comprising the step of reacting a triorganoboroxin of the formula (RI-BO)s with a trialkylborate of the formula B(OR 2 )a (wherein R 1 and R 2 are defined hereinafter). Furthermore, improved processes for the manufacture of organo-CBS catalysts using dialkoxyorganoboranes as starting material 25 and of trialkoxyboroxins are disclosed. In addition, new methods of using dialkoxyorganoboranes for the preparation of organo-CBS catalysts and in Suzuki-type coupling reactions are provided. Detailed Description of the Invention 30 According to the invention the process for the synthesis of the dialkoxyorganoboranes (3) of the formula R 1

-B(OR

2

)

2 involves an ester exchange reaction between a triorganoboroxin (1) of the formula (R 1

-BO)

3 and a trialkylborate (2) of the formula B(OR2), 35 wherein

R

1 is C1-C 20 alkyl, Cs-C 10 cycloalkyl, C6-C 1 4 aryl, C 7

-C

24 aralkyl, C-C 24 alkaryl, C 2

-C

2 0 alkenyl, C 5

-C

15 cycloalkenyl, C 2-

C

20 alkynyl, CH 2 SiMe 3 , substituted Ci-C2w alkyl and

R

2 is C 1 - C 20 alkyl, 40 or two R 2 groups in compounds 2 or 3 together with the - BOr moiety form a cyclic structure of the formula 3 0 -B Ra 0 with the divalent group R 3 selected from the group consisting of -CH2CHr, -CH(CH)CHr, -CH 2

CH

2

CH

2 r, -CH(CH 3 )CH(CH)-, -CH(CH2CH3)CH 2 -, C(CH4) 2

C(CH

3

)

2 -, 5 -CH 2

C(CH)

2 CHr-, -(CH2)e-, ortho-C 6

H

4 or ortho-Cea-salkyl With R 3 being a divalent group as defined above, the trialkylborates (2) may have the following dinuclear structure: R/ B-O-R3-O-B R 10 0 0 the resulting dialkoxyorganoboranes (3) may have the following cyclic structure: 0 R-B R3 0 15 Prefered derivatives prepared by the process according to the present invention are dialkoxyarganoboranes (3) of the formula R 1

-B(OR

2

)

2 , wherein R1 is methyl, ethyl, n propyl, isopropyl or n-butyl and R2 is isopropyl or n-butyl. 20 The reaction is preferably performed under exclusion of air and moisture. The dialkoxyorganoborane (3) is preferably separated from the reaction mixture by distillation. The reaction is preferably carried out in the presence of at least one non-coordinating solvent. Any non-coordinating solvent or mixtures thereof can be employed, preferably with a boiling point different (higher or lower) from that of the dialkoxyorganoborane (3) 25 prepared in order to facilitate its easy separation from the product. For instance, a mixture of two solvents having boiling points below that of compound (3) may be employed. It is also possible to for example use a mixture of two solvents having boiling points higher than that of compound (3) while it may also be advantageous to employ a mixture of solvents having boiling points below and above that of the 30 dialkoxyorganoborane (3) to be prepared. In most cases only one solvent will be employed. Examples are tetrahydrofurane (THF), diethylether, tert.-butylmethylether, hexane, pentane, toluene or benzene, preferably THF or toluene.

4 The temperature range for the synthesis is from -20'C and +120 0 C, preferably from O'C and 60*C, more preferably at about ambient temperatures such as from 20 to 30*C. The synthesis is usually performed at a pressure from 0.1 bar to 5 bar, preferably at normal pressure. The distillative isolation of the products can be carried out at a pressure from 5 0.01 bar to 1 bar, preferably at normal pressure. The mole ratio of the triorganoboroxin 1 to the alkylborate 2 can vary in a wide range. However, it is preferred that the mole ratio is in the range of approximately 1 : 2 to 1 : 4, preferably in the range of approximately I : 3. 10 Furthermore, when R 1 is methyl the trimethylboroxin (1a) can be prepared in a pre step in situ followed by the reaction of (1 a) with a trialkylborate (2) of the formula B(OR 2 )s, preferably in the same reactor. In this case diborane gas is reacted with carbon monoxide to yield the desired (1a) of the formula (H 3 C-BO)3 in THF solution (Scheme 1, Brown, 15 H.C. Organometallics 4, 816 (1984), Rathke, M.W.; Brown, H.C. J. Am. Chem. Soc. 88, 2606 (1966)). THF 3 B 2

H

5 + 6 CO ------ --- > 2 (H3C-BO)a 20 (1a) (R = CH3) Scheme 1 25 Another embodiment of the invention is therefore a process for the preparation of a dialkoxymethylborane (3a) of the formula HC-B(OR 2 )2, comprising the steps of a) reacting diborane with carbon monoxide in a solvent to form the trimethylboroxin 1 a of the formula (H3C-BO)s, 30 b) reacting the trimethylboroxin (1a) with a trialkylborate (2) of the formula B(OR 2

)

3 , and c) separating the dialkoxymethylborane from the reaction mixture by distillation, wherein R 2 is C1 - C 20 alkyl 35 or two R 2 groups in compound (2) together with the -BO2- moiety form a cyclic structure of the formula 0 -B Ra 0 5 with the divalent group R 3 selected from the group consisting of -CH 2

CH

2 -, -CH(CH3)CH2-,

-CH

2

CH

2

CH

2 -, -CH(CH 3

)CH(CH

3 )-, -CH(CH 2 CH3)CH 2 -, -C(CH 3

)

2 C(CH3) 2 -,

-CH

2

C(CH

3

)

2

CH

2 -, -(CH 2 )e-, ortho-CH 4 or ortho-CH 3 akyl. 5 According to another embodiment of the invention the synthesis of trialkoxyboroxins (4) of the formula (R 2 0-BO) 3 involves an ester exchange reaction between a triorgano boroxin (1) of the formula (R 1

-BO)

3 and a trialkylborate (2) of the formula B(OR 2

)

3 , wherein

R

1 is C 1 - C20 alkyl, C3 - C10 cycloalkyl, Ce - C14 aryl, C7 - C24 aralkyl, C7 - C24 alkaryl, C2 10 - C20 alkenyl, C5 - C15 cycloalkenyl, C2 - C20 alkynyl, CH 2 SiMe 3 , substituted CI - C2o alkyl and

R

2 is C1 - C20 alkyl. According to the invention the dialkoxyorganoboranes (3) can be employed for the syn 15 thesis of organo-oxazaborolidine catalysts (organo-CBS). The invention, the subject of the present application discloses a process for the prepara tion of organo-oxazaborolidines of the structural formula (6) R 4 R6 R N B-R 0 R R ,(6) 20 the process comprising the steps of a) reacting an 1,2-aminoalcohol of the formula (5) 25 HNR 4

-CR

5

R

6

CR

7 RB-OH (5) wherein 30 R 4 to RB is hydrogen, C1 - C20 alkyl, C6 - C14 aryl, C7- C24 aralkyl, Cr - C24 alkaryl, substituted C1-C20 alkyl or the two groups R 4 and R 5 together are a divalent group selected from the group consisting of -CH 2

CH

2 -, -CH(CH 3

)CH

2 -, -CH 2

CH

2

CH

2

-,

6

-CH(CH

3

)CH(CH

3 )-, -CH(CH 2 CH3)CH 2 -, -C(CH3) 2 C(CH3) 2 -, -CH2C(CH) 2 CH2- to form with the -NH-CR- moiety a cyclic structure, with a dialkoxyorganoborane 3 of the formula RI-B(OR 2

)

2 , wherein 5 R 1 is C1 - C20 alkyl, 03- C1 cycloalkyl, Ce - C14 aryl, Cr - C24 aralkyl, 07- C24 alkaryl, C2 - C20 alkenyl, C5 - C15 cycloalkenyl, C2 - C2a alkynyl, CH 2 SiMea, substituted C1 - C20 alkyl and

R

2 is C1 - C20 alkyl 10 or the two R 2 groups in compound (3) together with the -BOr moiety form a cyclic structure of the formula 0 -B R3 0 with the divalent group R 3 selected from the group consisting of -CH2CHa-, 15 -CH(CH3)CH-, -CH 2

CH

2

CH

2 -, -CH(CH 3

)CH(CH

3 )-, -CH(CH 2

CH

3

)CH

2- , -C(CH3)2C(CH3)-, -CH2C(CH3)2CH-, -(CH 2 )6-, ortho-CH 4 or ortho-CeH 3 alkyl, and b) heating the reaction mixture to complete the ring closure reaction and to distill off the formed alcohol. 20 Preferably chiral 1,2-aminoalcohols (5) are employed in this process. Chiral 1,2 aminoalcohols are characterized by the presence of at least one asymmetric carbon atom. Preferably 1,2-aminoalcohols (5) with different R 5 and R 6 groups and/or different R 7 and R 8 groups are employed. 25 Scheme 2 shows an example using diisopropoxymethylborane (3b) to prepare (S) MeCBS (6a) from (S)-diphenylprolinol (5a) (cf. US 4,943,635). Instead of water isopropanol is produced as a side product, which can easily be removed from the catalyst. 30 B H H0 H/ HH O- H + i-PrOH H4eat- H + IPrOH N H Toun fet+ /PO NH NH N-B P" -CH,\ (S)MecBS

CH

3 (Sa) (3b) (6a) 7 Scheme 2 The reaction mixture is heated in step b) of the process described above to a temperature sufficient to complete the ring closure reaction in short time, preferably in 5 less than 3 hours. This is usually achieved by heating the reaction mixture to the reflux temperature of the solvent or solvent mixture employed under normal pressure. Regular temperature ranges for this step are between about ambient temperatures and about + 120"C. 10 The process is usually performed at a pressure from 0.1 bar to 5 bar, preferably at normal pressure. The distillative separation of the formed alcohol can usually be carried out at a pressure from 0.01 bar to 1 bar, preferably at normal pressure. Another potential use of dialkoxyorganoboranes is in Suzuki-type C-C-bond coupling 15 reactions to transfer an organo group into a molecule. As used in connection with the present invention, the term alkyll" denotes a branched or an unbranched or a cyclic saturated hydrocarbon group comprising between 1 and 20 carbon atoms; examples are methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, 20 tert-butyl, amyl, isoamyl, sec-amyl, 1,2-dimethylpropyl, 1,1-dimethylpropyl, hexyl, 4 methylpentyl, 1-methylpentyl, 2-methylpentyl, 3- methylpentyl, 1,1-dimethylbutyl, 2,2 dimethylbutyl, 3,3-dimethylbutyl, 1,2-dimethylbuty, 1,3-dimethylbutyl, 1,2,2 trimethylpropyl, 1,1,2-trimethylpropyl, heptyl, 5-methylhexyl, 1-methylhexy, 2,2 dimethylpentyl, 3,3-dimethyl pentyl, 4,4-dimethylpentyl, 1,2-dimethylpentyl, 1,3 25 dimethylpenty, 1,4-dimethylpentyl, 1,2,3-trimethylbutyl, 1,1,2-trimethylbutyl, 1,1,3 trimethylbutyl, octyl, 6-methylheptyl, 1-methylheptyl, 1,1,3,3-tetramethylbutyl, nonyl, 1-, 2-, 3-, 4-, 5-, 6- or 7-methyloctyl, 1-, 2-, 3-, 4- or 5-ethylheptyl, 1-, 2- or 3-propylhexyl, decyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- and 8-methylnonyl, 1-, 2-, 3-, 4-, 5- or 6-ethyloctyl, 1-, 2-, 3 or 4-propylheptyl, undecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8- or 9-methyldecyl, 1-, 2-, 3-, 4-, 5-, 6 30 or 7-ethylnonyl, 1-, 2-, 3-, 4- or 5-propyloctyl, 1-, 2- or 3-butylheptyl, 1-pentylhexyl, dodecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7-, 8-, 9- or 10-methylundecyl, 1-, 2-, 3-, 4-, 5-, 6-, 7- or 8 ethyldecyl, 1-, 2-, 3-, 4-, 5- or 6-propylnonyl, 1-, 2-, 3- or 4-butyloctyl, 1-2-pentylheptyl and isopinocampheyl. Preferred are the alkyl groups methyl, ethyl, propyl, isopropyl, butyl, isobutyl, sec-butyl, tert-butyl, amyl, isoamyl, sec-amyl, 1,2-dimethylpropyl, 1,1 35 dimethylpropyl. The term "cycloalkyl" denotes a saturated hydrocarbon group comprising between 3 and 10 carbon atoms including a mono- or polycyclic structural moiety. Examples are cyclopropyl, cyclobutyl, cyclopenty, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl or 40 cyclodecyl. Prefered are the cycloalkyl groups cyclopropyl, cyclopentyl and cyclohexyl.

8 The term "substituted alkyl" denotes an alkyl group with at least one hydrogen atom is replaced by a halide atom like fluorine, chlorine, bromine or iodine or by an alkoxy group. The term "alkoxy" stands for a group derived from an aliphatic monoalcohol with between 5 1 and 20 carbon atoms. The term "alkenyl" denotes a straight chainor branched unsaturated hydrocarbon group comprising between 2 and 20 carbon atoms including at least one carbon-carbon double bond. Examples are vinyl, allyl, 1-methylvinyl, butenyl, isobutenyl, 3-methyl-2- butenyl, 1 10 pentenyl, 1-hexenyl, 3-hexenyl, 1-heptenyl, 3-heptenyl, 1-octenyl, 1-nonenyl, 2-nonenyl, 3-nonenyl, 1-decenyl, 3-decenyl, 1,3-butadienyl, 1-4,pentadienyl, , 1,3-hexadienyl, 1,4 hexadienyl. Preferred are the alkenyl groups vinyl, allyl, butenyl, isobutenyl and 1,3 butadienyl. 15 The term "cycloalkenyl" denotes an unsaturated hydrocarbon group comprising between 5 and 15 carbon atoms including at least one carbon-carbon double bond and a mono- or polycyclic structural moiety. Examples are cyclopentenyl, 1 -methylcyclopentenyl, cyclohexenyl, cyclooctenyl, 1,3-cyclopentadienyl, 1,3-cyclohexadienyl, 1,4 cyclohexadienyl, 1,3-cycloheptadienyl, 1,3,5-cycloheptatrienyl and 1,3,5,7 20 cyclooctatetraenyl. The term "alkynyl" denotes a straight chain or branched unsaturated hydrocarbon group comprising between 2 and 20 carbon atoms including at least one carbon-carbon triple bond. Examples of alkynyl groups include ethynyl, 2-propynyl and 2- or 3-butynyl. 25 The term "aryl" denotes an unsaturated hydrocarbon group comprising between 6 and 14 carbon atoms including at least one aromatic ring system like phenyl or naphthyl or any other aromatic ring system. ortho-CH 4 denotes a divalent aryl group occurring in catechol-type derivatives. 30 The term "aralkyl" denotes an aryl-substituted alkyl group comprising between 7 and 24 carbon atoms including for example a phenyl-, naphthyl- or alkyl-substituted phenyl- or alkyl-substituted naphthyl-group or any other aromatic ring system. Examples of aralky groups include benzyl, 1- or 2-phenylethyl, 1-, 2- or 3-phenylpropyl, mesityl and 2-, 3- or 35 4-methylbenzyl groups. The term "alkaryl" denotes an alkyl-substituted aryl group comprising between 7 and 24 carbon atoms including for example a phenyl- or naphthyl- or alkyl-substituted phenyl- or alkyl-substituted naphthyl-group or any other aromatic ring system and an alkyl 40 substituent as defined above. Examples for alkaryl groups are 2,- 3- or 4-methylphenyl, 2,- 3- or 4-ethylphenyl and 2,- 3-, 4-, 5-, 6-, 7- or 8-methyl-1-naphthyl groups. ortho- 9 CoHalkyl denotes an alkyl-substituted divalent aryl group occurring in catechol-type derivatives. Examples 5 The following examples illustrate the present invention without limitation of the same. Example 1: Synthesis of diisopropoxymethylborane 10 Triisopropylborate (110 g, 0.585 mol) was added to trimethylboroxin (55 ml of a 50 wt% solution of trimethylboroxin in THF, 0.20 mol) under nitrogen and stirred for 5 minutes. The resulting clear solution was heated to distill off the desired diisopropoxymethylborane through a Vigreux column. The first fraction (22 g, distilling between 66-71 *C) contained mostly THF and a small amount of isopropanol. The second fraction (53 g, distilling 15 between 74-100 *C) contained 81 wt% diisopropoxymethylborane and 19 wt% THF. The third fraction (24 g, distilling between 100-112 *C) contained 87 wt% diisopropoxymethylborane and 13 wt% triisopropoxyboroxin. The overall yield of diisopropoxymethylborane was 75.8 % relative to the borate employed. 20 Example 2: Synthesis of dilsopropoxymethylborane with preceding formation of trimethylboroxin Trimethylboroxin was prepared in a pressure reactor by addition of diborane (86 g, 3 moles) and carbon monoxide (excess) into THF (150 ml) containing lithium borohydride 25 catalyst (0.25 g). The reaction temperature was kept below 50*C during the gas addition. Some of the diborane was swept from the reactor by the excess CO vented, therefore the final amount of solution obtained was 197 g. The resulting concentration of trimethylboroxin in THF was 39.3 wt% by boron analysis. This solution containing 77 g trimethylboroxin was combined with triisopropylborate (348.8 g, 1.85 mol). The mixture 30 was fractionally distilled. The first fraction (100 ml, 70-88*C) contained THIF, diisopropoxymethylborane and pyrophoric trimethylborane as an impurity and was discarded. Fraction 2 (90 ml, distilled between 88-98*C) and fraction 3 (150 ml, distilled between 98-120"C) both contained primarily diisopropoxymethylborane (impurities < 5 %), giving an estimated yield of about 70 %. 35 Example 3: Synthesis of Methyldi-n-butoxyborane Trimethylboroxin (50 ml of 50 wt% solution in THF, 170 mmol) was placed in a round bottom flask with distillation head and receiver under nitrogen. Tri-n-butyl borate (92 ml, 40 340 mmol) was added and the mixture stirred 30 min. Methyldi-n-butoxyborane and THIF were distilled from the tri-n-butoxyboroxin. The methyldi-n-butoxyborane and THF were separated by further distillation to obtain 44 g of methyldi-n-butoxyborane, 50% yield.

10 Example 4: Synthesis of (S)-MeCBS from Methyldi-n-butoxyborane (S)-Diphenylprolinol (DPP) (0.58g, 2.3 mmol) along with 15 ml of toluene were added to a 50 ml three-neck round bottom flask fitted with a distillation head and condenser and 5 flushed with nitrogen. While remaining under inert atmosphere, methyldi-n-butoxyborane (0.60 g, 2.3 mmol) was added via syringe to the flask. The reaction contents were heated to 1 10"C while stirring for 1 hour. While the 11B NMR spectrum of the reaction mixture showed the formation of intermediates 6 = 9.7 ppm), additional methyldi-n-butoxyborane (0.06 g, 0.23 mmol) was added followed by heating for 4 hours. All toluene and 1-butanol 10 were distilled from the clear reaction mixture (azeotrope boiling point 106 0 C). Toluene was added to the residue. The 11 B NMR spectrum of the toluene solution showed com plete formation of (S)-MeCBS (6 = 35 ppm, broad singlet). The 1 H NMR spectrum (CDCla) of the product also indicated no remaining (S)-DPP or unreacted methyldi-n butoxyborane. 15 Comprises/comprising and grammatical variations thereof when used in this specification are to be taken to specify the presence of stated features, integers, steps or components or groups thereof, but do not preclude the presence or addition of one or more other fea tures, integers, steps, components or groups thereof.

Claims (14)

1. A process for the preparation of organo-oxazaborolidines of the structural for mula (6) R4 RG R" N B-R 5 R , (6) the process comprising the steps of a) reacting an 1,2-aminoalcohol of the formula (5) 10 HNR 4 -CR 5 R 6 CR 7 Ra-OH (5) 15 wherein R 4 to RE is hydrogen, C1 - C20 alkyl, Ce - C14 aryl, C7 - C24 aralkyl, C -C24 alkaryl, substituted C1-C20 alkyl or the two groups R 4 and R 5 together are a divalent group selected from the group consisting of -CH 2 CH 2 -, -CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 -, 20 -CH(CH 3 )CH(CH3)-, -CH(CH 2 CH3)CH 2 -, -C(CH 3 ) 2 C(CH 3 ) 2 -, -CH 2 C(CH3)2CH2- to form with the -NH-CR 6 - moiety a cyclic structure, with a dialkoxyorganoborane (3) of the formula R 1 -B(OR 2 ) 2 , wherein R 1 is C1 - C20 alkyl, C3 - C10 cycloalkyl, Ce - C14 aryl, C7 - C24 aralkyl, C7 25 C24 alkaryl, C2 - C20 alkenyl, Cs - C15 cycloalkenyl, C2 - C20 alkynyl, CH 2 SiMe 3 , substituted C1 - C20 alkyl and R 2 is C1 - C20 alkyl or the two R 2 groups in compound (3) together with the -B0 2 - moiety form a 30 cyclic structure of the formula 0 -B R3 0 12 with the divalent group R 3 selected from the group consisting of -CH 2 OH 2 -, -CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 -, -CH(CH3)CH(CH 3 )-, -CH(CH 2 CH 3 )CH 2 -, -C(CH3)2C(CH 3 ) 2 -, -CH 2 C(CH 3 ) 2 CH 2 -, -(CH 2 )e-, ortho-C 6 H 4 or ortho C 6 H 3 aIkyl, and 5 b) heating the reaction mixture to complete the ring closure reaction and to distill off the formed alcohol.

2. The process according to claim 1 wherein the 1,2-aminoalcohol (5) is chiral. 10

3. A process for the preparation of a dialkoxyorganoborane (3) of the formula R 1 -B(OR 2 ) 2 , comprising the step of reacting a triorganoboroxin (1) of the formula (R 1 -BO) 3 and a trialkylborate (2) of the formula B(OR 2 ) 3 , wherein 15 R 1 is C1-C20 alkyl, C3-C10 cycloalkyl, 06-C14 aryl, C7-C24 aralkyl, C7-C24 alkaryl, C2 C20 alkenyl, C,-C,5 cycloalkenyl, C2-C20 alkynyl, CH2SiMeS, substituted Cr1C20 alkyl and R 2 is C1 - C20 alkyl, 20 or two R 2 groups in compounds (2) or (3) together with the - B0 2 - moiety form a cyclic structure of the formula 0 -B R3 0 with the divalent group R 3 selected from the group of consisting of-CH2CH2-, 25 CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 -, -CH(CH 3 )CH(CH3)-, -CH(CH 2 CH3)CH 2 -, -C(CH3) 2 C(CH 3 ) 2 -, -CH 2 C(CH 3 ) 2 CH 2 -, -(CH 2 ) 6 -, ortho-C 6 H 4 or ortho-C 6 H 3 alkyl.

4. The process of claim 3, wherein the dialkoxyorganoborane (3) is separated from the reaction mixture by distillation. 30

5. The process of claim 3, wherein R 1 is methyl, ethyl, n-propyl, isopropyl or n-butyl and R 2 is isopropyl or n-butyl.

6. The process of claim 3, wherein the reaction is carried out in the presence of at 35 least one non-coordinating solvent.

7. The process of claim 4, wherein the solvent is tetrahydrofurane (THF), diethyl ether, tert.-butylmethylether, hexane, pentane, toluene or benzene. 13

8. The process of claim 3, wherein the mole ratio of the triorganoboroxin (1) to the trialkylborate (2) is in the range of approximately 1 : 2 to 1 : 4.

9. The process of claim 1, wherein the reaction is carried out at a temperature from 5 - 20 0 C to+ 120 0 C.

10. A process for the preparation of a dialkoxymethylborane (3a) of the formula H 3 C B(OR 2 ) 2 , comprising the steps of 10 a) reacting diborane with carbon monoxide in a solvent to form the trimethyl boroxin 1 a of the formula (H 3 C-BO) 3 , b) reacting the trimethylboroxin (1a) with a trialkylborate (2) of the formula B(OR 2 ) 3 , and c) separating the dialkoxymethylborane (3a) from the reaction mixture by dis 15 tillation, wherein R 2 is C1-C20 alkyl or two R 2 groups in compounds (2) or (3a) together with the - B0 2 - moiety form a cyclic structure of the formula 0 -B R3 20 0 with the divalent group R 3 selected from the group of consisting of-CH 2 CH 2 -, -CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 -, -CH(CH 3 )CH(CH)-, -CH(CH 2 CH 3 )CH 2 -, -C(CH 3 ) 2 C(CH 3 ) 2 -, -CH 2 C(CH 3 ) 2 CH 2 -, -(CH 2 ) 6 -, ortho-C 6 H 4 or ortho-C 6 H 3 alkyl. 25

11, A process for the preparation of a trialkoxyboroxin (4) of the formula (R 2 0-BO) 3 , comprising the step of reacting an triorganoboroxin (1) of the formula (R 1 -BO)3 and a trialkylborate (2) of the formula B(OR 2 ) 3 , wherein 30 R 1 is C 1 -C 20 alkyl, C3-C10 cycloalkyl, C6-C14 aryl, C7-C24 aralkyl, C7-C24 alkaryl, C2 C20 alkenyl, Cs-C5 cycloalkenyl, C2-C20 alkynyl, CH 2 SiMe 3 , substituted C1-C20 alkyl and R 2 is C1 - C20 alkyl. 35

12. A method of using dialkoxyorganoboranes (3) of the formula R 1 -B(OR 2 )2 for the preparation of organo-oxazaborolidine catalysts (organo-CBS catalysts), wherein R 1 is C - C20 alkyl, C3 - C10 cycloalkyl, Ce - C14 aryl, C7 - C24 aralkyl, Cy - C24 al karyl, C2 - C20 alkenyl, C5 - C15 cycloalkenyl, C2 - C20 alkynyl, CH 2 SiMe 3 , substi 40 tuted C1 - C20 alkyl 14 and R 2 is C1 -C20 alkyl, or the two R 2 groups in compounds (3) together with the -B0 2 - moiety form a cy clic structure of the formula 0 -B R3 5 0 with the divalent group R 3 selected from the group consisting of -CH 2 CH 2 -, CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 -, -CH(CH 3 )CH(CH 3 )-, -CH(CH 2 CH 3 )CH 2 -, C(CH 3 ) 2 C(CH3) 2 -, -CH 2 C(CH3) 2 CH2-, -(CH 2 ) 6 -, ortho-CH 4 or ortho-C 6 H 3 alkyl. 10

13. A method of using dialkoxyorganoboranes (3) of the formula R1-B(OR 2 ) 2 in Su zuki-type coupling reactions, wherein R 1 is CI - C20 alkyl, C 3 - C10 cycloalkyl, C6 - C14 aryl, C7 - C24 aralkyl, C7 - C24 al karyl, C2 - C20 alkenyl, C - Cs cycloalkenyl, C2 - C2o alkynyl, CH 2 SiMe 3 , substi 15 tuted C1 - C2o alkyl and R 2 is C1 -C2 alkyl, or the two R 2 groups in compounds (3) together with the -B0 2 - moiety form a cy clic structure of the formula 0 -B R 20 0 with the divalent group R 3 selected from the group consisting of -CH 2 CH 2 -, CH(CH 3 )CH 2 -, -CH 2 CH 2 CH 2 -, -CH(CH3)CH(CH3)-, -CH(CH 2 CH 3 )CH 2 -, C(CH3) 2 C(CH3) 2 -, -CH 2 C(CH3) 2 CH 2 -, -(CH2)s-, ortho-C 6 H 4 or ortho-CH3alkyl. 25

14. The compound produced by the process according to claim 1 or claim 2. BASF SE 30 WATERMARK PATENT AND TRADE MARKS ATTORNEYS P29631 AU01