Chiral cyanohydrin nucleophilic addition

The following results indicate that there are essentially two modes by which these cyanohydrins form. The first is a Lewis acid-catalyzed mode which presumably activates the carbonyl toward addition, and the second is a nucleophilic mode whereby the nucleophile reacts with TMSCN to release CN which adds to the carbonyl followed by silylation of the oxygen. There is also a large body of literature on the preparation of chiral cyanohydrins. ... 

It is of some historical interest that Kiliani s cyanohydrin synthesis (24) enabled Emil Fischer (25) to carry out the first asymmetric synthesis. Lapworth (26) used this base-catalyzed nucleophilic 1,2-addition reaction in one of the first studies of a reaction mechanism. Bredig (27,28) appears to have been the first to use quinine (29) in this reaction as the chiral basic catalyst. More recently, others (20) have used basic polymers to catalyze the addition of cyanide to aldehydes. The structure of quinine has been known since 1908 (30). Yet it is of critical importance that Prelog s seminal work on the mechanism of this asymmetric transformation (eq. [4]) could not have begun (16) until the configuration of quinine was established in 1944 (31,32). 

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