6-Keto esters, acylation cyanides

The reaction between dialkyl phosphorocyanatidite and acyl cyanides in dichloro-methane at 0 °C parallels that between the same phosphite and 1,2-dicarbonyl compounds, and is probably initiated by attack of tervalent phosphorus on the carbonyl group the formation of O- and V-alkyl products, (30) and (29), is an indication of the probable nature (28) of an intermediate.25 The extension of the reaction (see Organophosphorus Chemistry , Vol. 7, pp. 108, 126) to include ethyl phosphorodicyanatidite and 1-keto-esters provides a route to the 5-phosphabicyclo-[3,2,0]heptanes (31) in high yields.26... 

Specific enol equivalents (e. g. (3-keto esters) and umpolung (e. g., with cyanide or acetylide ions as acyl anion equivalents) have of course been used in synthesis for many years. What is new is the recognition of their role, as a result of the disconnec-... 

The use of alpine-borane (3) has also been extended to include the reduction of acyl cyanides (14) to optically active p-amino alcohols (15),10 as well as the reduction of a-keto esters (16) into the corresponding a-hydroxy esters (17). ... 

Johnson s group developed a catalytic asymmetric cyanation/1,2-Brook rearrangement/C-acylation of acylsilanes with cyanoformates (Scheme 19.14). In the presence of (i ,/ )-(salen)Al 19, the corresponding cyanohydrin trimethylsilyl ethers of a-keto esters were obtained in moderate to good enantioselectivities (61-82% enantiomeric excess). Access to chiral (silyloxy)nitrile anions is facilitated by metal cyanide-promoted Brook rearrangement reaction of acylsilanes. 

In the presence of sodium ethoxide, nitriles having reactive a methylene groups may be acylated with esters to form /S-keto nitriles. The method is general and is illustrated by the reaction of alkyl cyanides, where R is C, to with ethyl benzoate to form the corresponding alkylbenzoyl-... 

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