TRIARYL BORANE CATALYSTS AND METHOD FOR SELECTIVE HYDROSILYLATION OF ESTERS AND LACTONES USING SAID CATALYSTS

The present invention relates to a catalytic process for the partial reduction of esters or lactones to silyl acetals, which upon hydrolysis give aldehydes, using silanes as reducing agents, preferably triethylsilane (TESH) or 1,1,3,3-tetramethyldisiloxane (TMDS), in the presence of novel triaryl borane type catalysts. More specifically, the present invention relates to novel triaryl borane type catalyst compounds of formula (I) which can be applied for the partial reduction of an ester or lactone to a silyl acetal. In the formula R1, R′1, R5, R′5 and R6 are groups having small steric demand and R10 is a group having large steric demand. The invention also relates to N a method for the preparation of aldehydes or lactols wherein said method comprises the following steps: i) an ester or lactone is reacted with a silane in the presence of a compound of formula (I) to obtain a silyl acetal; ii) the obtained silyl acetal is hydrolysed with acidic or fluoride containing reagent to form an aldehyde or lactol; iii) optionally, the resulting aldehyde or lactol is separated and purified.