RU2327679C1 - Method of obtaining 1,2,3,4-tetraalkyl-1,4-diiodine-1,3-butadienes - Google Patents

Abstract

FIELD: chemistry; obtaining of butadienes.

SUBSTANCE: process is achieved through reaction of 1,2-disubstituted acetylenes with n-BuMgCl, I₂ and CuCl in the presence of a zirconocene dichloride catalyst in diethyl ether at 20°C and in molar ratio R-≡-R:h-BuMgCl:Cp₂ZrCl₂ equal to 10:(22-26):(1.0-1.4). Addition of copper chloride (I) and I₂ ether solution is done at 0°C and in molar ratio of components n-BuMgCl:I₂ = 1:1.1 and R-≡-R:CuCl = 10:1. The reaction mixture is then mixed in argon at 20°C for 3-5 hours.

EFFECT: high selectivity of butadienes.

1 cl, 1 tbl, 9 ex

Description

The present invention relates to organic chemistry, specifically to an improved method for producing 1,2,3,4-tetraalkyl-1,4-diiod-1,3-butadiene of the general formula (I):

where R = C ₂ H ₅ , nC ₃ H ₇ , nC ₄ H ₉

Substituted 1,4-diiod-1,3-butadiene can be used in fine organic and organometallic synthesis as starting intermediates in the preparation of complexes based on transition metals, substituted thiophenes, furans, cyclopentadienes and pyridines, as well as in the preparation of substances possessing biological activity.

The known method ([1], S. Yamaguchi, R.-Z. Jin, K. Tamao and F. Sato. A Convenient Synthesis of Diiodobutadiene and their Derivatization to Siloles // J. Org. Chem., 63, (1998) , 10060-10063) for the preparation of substituted 1,4-diiodo-1,3-butadiene (2) in 40-68% yield by reaction of diacetylenes with Pr ⁱ MgCl in the presence of a stoichiometric amount of Ti (OPr ⁱ ) ₄ in diethyl ether at -50 ° C, followed by processing the reaction mass with an ethereal solution of I ₂ at -50 ° C according to the scheme:

In a known manner, 1,2,3,4-tetraalkyl-1,4-diiod-1,3-butadiene (1) cannot be obtained.

The known method ([2], U. Bankwitz, H. Sohn, DR Powell, R. West. Synthesis, solid-state structure, and reduction of 1,1-dichloro-2,3,4,5-tetramethylsilole // J. Organomet.Chem., 499 (1995), C7-C9) for the preparation of 1,4-diiod-1,3-butadiene (1) by reacting 1,2-disubstituted acetylenes with a stoichiometric amount of zirconacenedichloride (Cp ₂ ZrCl ₂ ) pretreated with two equivalents of butyl lithium (n-BuLi) at -78 ° C in tetrahydrofuran, followed by the addition of I ₂ at a temperature of -78 ° C in the presence of 2 equiv. CuCl according to the scheme:

The known method for producing 1,2,3,4-tetraalkyl-1,4-diiodo-1,3-butadiene (1) involves the use of a stoichiometric amount of expensive zirconacenedichloride (Cp ₂ ZrCl ₂ ), pyrophoric n-BuLi, in addition, this process energy-consuming, since during the reaction it is necessary to maintain a low temperature of -78 ° C.

An improved method for the synthesis of 1,2,3,4-tetraalkyl-1,4-diiod-1,3-butadiene (1) is proposed.

The essence of the method consists in the interaction of disubstituted acetylenes of the formula R-≡-R, where R = C ₂ H ₅ , n-C ₃ H ₇ , n-C ₄ H ₉ , with n-BuMgCl in the presence of Cp ₂ ZrCl ₂ zirconacenedichloride catalyst taken in a molar ratio of R-≡-R: n-BuMgCl: Cp ₂ ZrCl ₂ = 10: (22-26) :( 1.0-1.4), preferably 10: 24: 1.2, for 3 hours, followed by addition to the reaction mass at 0 ° C ether solution of I ₂ in an amount of 1.1 mole equivalents with respect to BuMgCl and CuCl in an amount of 0.1 mole equivalents with respect to acetylene reaction mass with stirring under argon at room order erature (~ 20 ° C) and atmospheric pressure for 3-5 hours. The yield of target products is 45-57%. It is necessary to use diethyl ether as a solvent; in other ethereal solvents (THF, dioxane), the yield of the target products (1) is significantly reduced.

The reaction proceeds according to the scheme:

R = C ₂ H ₅ , n-C ₃ H ₇ , n-C ₄ H ₉

The target products (1) are formed only with the participation of disubstituted acetylene, n-BuMgCl, I ₂ and the catalyst Cp ₂ ZrCl ₂ . In the presence of other catalysts based on transition metal complexes (for example, Zr (acac) ₄ , Cp ₂ TiCl ₂ , Pd (acac) ₂ , Ni (acac) ₂ , Fe (acac) ₃ ), the target products (1) are not formed.

The reaction in the presence of a catalyst Cp ₂ ZrCl ₂ more than 14 mol. % with respect to acetylene does not lead to a significant increase in the yield of the target products (1). The use of Cp ₂ ZrCl ₂ in the reaction of the catalyst less than 10 mol.% Reduces the yield of MOS (1), which is associated with a decrease in catalytically active centers in the reaction mass. The experiments were carried out at room temperature ~ 20 ° C. At a higher temperature (for example, 50 ° C), the content of compaction products increases, at a lower temperature (for example, 0 ° C) the reaction rate decreases.

A change in the ratio of the starting reagents in the direction of increasing the content of n-BuMgCl with respect to acetylene does not lead to a significant increase in the yield of the target products (1). A decrease in the amount of n-BuMgCl with respect to acetylene decreases the yield of MOC (1).

Significant differences of the proposed method

1. In the proposed method, available n-BuMgCl and catalytic amounts of Cp ₂ ZrCl ₂ are used as a starting reagent. In the known method, 1,4-diiod-1,3-butadiene (1) is obtained from stoichiometric amounts of Cp ₂ ZrCl ₂ and butyllithium with an additional reduction step of Cp ₂ ZrCl _{2 with} butyllithium at low temperature.

The proposed method has the following advantages

1. The method allows to obtain with high selectivity 1,2,3,4-tetraalkyl-1,4-diiod-1,3-butadiene (1) using not stoichiometric, but catalytic amounts of expensive zirconacenedichloride without the use of pyrophoric n-BuLi.

The method is illustrated by the following examples.

EXAMPLE 1. In a 50 ml glass reactor mounted on a magnetic stirrer, 1.2 mmol of Cp ₂ ZrCl ₂ , 10 mmol of oct-4-in, and 24 mmol of n-BuMgCl (2M solution in Et ₂ O). Stirred at room temperature for 3 hours. Next, the reaction mass is cooled to 0 ° C, 1 mmol of CuCl is added and 26.4 mmol of I ₂ (ether solution) is added dropwise. The temperature was brought to room temperature and stirred for 4 hours. An individual 4,7-diiod-5,6-dipropyl-4,6-decadiene (3) is obtained with a yield of 51%.

Spectral characteristics of 4,7-diiod-5,6-dipropyl-4,6-decadiene (3).

¹³ C NMR spectrum (δ, ppm): 13.57 (C ^13.16 ), 14.44 (C ^1.10 ), 22.45 (C ^2.9 ), 22.51 (C ^12.15 ), 32.32 (C ^{11, 14} ), 54.75 (C ^3.8 ), 115.18 (C ^4.7 ), 158.8 (C ^5.6 ).

Other examples confirming the method are shown in table 1.

Table 1 №№ R-≡-R The molar ratio of RC≡CR: n-BuMgCl: I ₂ : CuCl: Cp ₂ ZrCl ₂ , mmol Reaction time, h Yield (1),% one hex-3-in 10: 24: 26.4: 1: 1.2 7 53 2 '' 10: 26: 28.6: 1: 1.2 7 55 3 '' 10: 22: 24.2: 1: 1.2 7 49 four '' 10: 24: 26.4: 1: 1.4 7 57 5 '' 10: 24: 26.4: 1: 1.0 7 45 6 '' 10: 24: 26.4: 1: 1.2 8 54 7 '' 10: 24: 26.4: 1: 1.2 6 46 8 oct-4-in 10: 24: 26.4: 1: 1.2 7 51 9 dec-5-in 10: 24: 26.4: 1: 1.2 7 47

All experiments were carried out at room temperature (~ 20 ° C) in diethyl ether.

Claims (1)

The method of obtaining 1,2,3,4-tetraalkyl-1,4-diiod-1,3-butadiene of the General formula (I)

, where R = C ₂ H ₅ , n-C ₃ H ₇ , n-C ₄ H ₉ , including the interaction of 1,2-disubstituted acetylenes with an organometallic compound in the presence of a catalyst of zirconacene dichloride (Cp ₂ ZrCl ₂ ) in a solvent medium, followed by the addition of I ₂ in the presence of CuCl, characterized in that BuMgCl is used as the organometallic compound at a molar ratio R-≡-R: n-BuMgCl: Cp ₂ ZrCl ₂ = 10: (22-26) :( 1.0-1.4) , the reaction is carried out in diethyl ether at 20 ° C, and the subsequent addition of copper (I) chloride and ether solution I _{2 is} carried out at 0 ° C and a molar ratio of components of n-BuMgCl: I ₂ = 1: 1. 1 and R-≡-R: CuCl = 10: 1, then the reaction mass is stirred in argon at 20 ° C for 3-5 hours