Cyanide ion promoted addition of acyl phosphonates to ethyl cyanoformate:: Synthesis of tertiary carbinols via tandem carbon-carbon bond formations

[GRAPHICS] New cyanation/phosphonate -phosphate rearrangement/Cacylation reactions of cyartophosphate anion with cyanoformate esters are described. Phase-transfer cocatalysts facilitate cyanide-catalyzed reactions between acyl phosphonates and cyanoformates to afford protected tertiary carbinol products in good to excellent yields (74-95%). Ethyl cyanoformate is used as a cyanide source and electrophile. The scope of the reaction was investigated by using a number of benzoyl and acyl phosphonates along with ethyl cyanoformate. Representative chemoselective reduction of the product 5a afforded ethyl 3-amino-2- iydroxy-2-phenylpropanoate (13) in good yield.