Biellmann alkylation

Thioallyl and Related Anions. Alkylation of thioallyl anions, often termed Biellmann alkylation, represents a useful method for forming new C—C bonds, as illustrated by the synthesis of dendrolasin (49), which is a furanoterpene... 

In view of the synthetic applications, among carbanions stabilized by only one divalent sulfur atom, allylic thiocarbanions proved to be particularly valuable, as shown with Biellmann coupling of allylic groups, applied to an elegant synthesis of squalene from farnesyl bromide [301]. In this synthesis, the retention of the allylic double bond position and stereochemistry in both the metallation-alkylation and the desulfurization steps are noteworthy. However, the results are not always as clear-cut, and... 

The full details of the synthesis of squalene by Biellmann and Ducep have appeared (see Vol. 1, p. 161). This synthesis can be readily adapted for the introduction of tritium by quenching the ylide (8) with tritiated water before the alkylation step. 

The regioselectivity of alkylation and carbonyl addition of various thioallyl anions has been examined, particularly with regard to chelation and ion-pairing effects. Thus, Biellmann and co-workers have found that thioallyl-lithium (50), in the presence of [2,2,2]cryptate, adds to acetone exclusively from the... 

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