Search

A new multicomponent reaction leading to the formation of an imidazole ring was discovered: N,N′-diaryl-1,4-diazabuta-1,3-dienes reacted with trialkyl orthoformates, chloro(trimethyl)silane and water to give N,N′-1,3-diaryl-4-oxoimidazolinium salts or their tautomers, 4-hydroxyimidazolium salts. [ABSTRACT FROM AUTHOR]

In this paper, we describe the effectiveness of the combination between an organic solvent system mixture with orthoformates with different chain sizes from one to four carbon atoms. These orthoesters have been used as a "water trapper/alcohol releaser molecule" to reach a notable improvement in enantioselectivity and enantiomeric excess of our target compound, (S)-2-(4-isobutylphenyl)propanoic acid (ibuprofen eutomer), during the enzymatic kinetic resolution of rac-ibuprofen using immobilized lipase B of Candida antarctica as a biocatalyst. At the same time, one of the great problems of biocatalysis in organic media has been solved by eliminating excess water in the medium that allows the reversibility of the reaction. Following the optimization of the reaction conditions, an increase in enantiomeric excess and enantioselectivity was reached by using these acyl donors in the presence of a cosolvent. [ABSTRACT FROM AUTHOR]

In this paper, we describe the effectiveness of the combination between an organic solvent system mixture with orthoformates with different chain sizes from one to four carbon atoms. These orthoesters have been used as a “water trapper/alcohol releaser molecule” to reach a notable improvement in enantioselectivity and enantiomeric excess of our target compound, (S)-2-(4-isobutylphenyl)propanoic acid (ibuprofen eutomer), during the enzymatic kinetic resolution of rac-ibuprofen using immobilized lipase B of Candida antarctica as a biocatalyst. At the same time, one of the great problems of biocatalysis in organic media has been solved by eliminating excess water in the medium that allows the reversibility of the reaction. Following the optimization of the reaction conditions, an increase in enantiomeric excess and enantioselectivity was reached by using these acyl donors in the presence of a cosolvent.

The development of a new, highly efficient, and simple method for masking carbonyl groups as acetals and ketals is described. This methodology relies on the nature of the palladium catalyst to direct the acetalization/ketalization reaction. This new protocol is mild and proceed with a very low catalyst loading at ambient temperatures. The method has been extended to a wide variety of different carbonyl compounds with various steric encumbrances to form the corresponding acetals and ketals in excellent yields. [ABSTRACT FROM AUTHOR]

Fluoroform (CHF 3 ) reacts with alkali metal alkoxides MOR (M = Na, K) in the corresponding alcohols ROH (R = Me, Et, i -Pr, t -Bu, and Allyl) at 80–120 °C to give orthoformate esters HC(OR) 3 in 55–90% yield. Particularly notable is the formation of HC(OBu- t ) 3 in 75–80% yield (62% isolated yield; X-ray), an exotic organic compound that has been previously synthesized only once (3% yield). Solutions of NaOH in ROH (R = Me, Et, i -Pr and t -Bu) react with CHF 3 to give NaF, HCOONa, and orthoformates HC(OR) 3 . Hydrolysis of fluoroform with MOH (M = Na, K) at 140 °C produces largely MF and HCOOM along with small quantities of CO. [ABSTRACT FROM AUTHOR]

The reactions of triethyl, diethyl phenyl, or tributyl orthoformate with 1,3-dialkylaluminacyclopentanes results in regioselective cleavage of the sterically less hindered Al—C(5) bond; hydrolysis of the reaction mixture gives 4-methyl aldehyde acetals. In the case of more inert orthoformates, the process is activated with catalytic amounts of ZrCl4. [ABSTRACT FROM AUTHOR]