Oxirane reactions with alkyllithium

A general method for the preparation of 3,7-substituted allyl alcohols with (Z)-configuration has been developed with alkyllithium. The regioselectivity of the reactions of alkynyllithium and oxiranes ° ° and the effects of the solvent and (Me2N)3PO ° have been investigated with regard to the formation of homo-propargyllic alcohols. The stereochemistry of the process has been studied in the reactions of as- and fra 5-neopentylallyllithium with cyclohexene oxide and fra s-2,3-butene oxide. 

The reaction of alkyllithium with oxirane yields the same products as in the reaction with the Grignard reagent (Eq. 283). 

The reaction of oxiranes with base can follow several paths, giving products of type (34-38 Scheme 27). (a) Formation of an oxiranyl anion (34) is rare (Section 5.05.3.5). (b) Nucleophilic ring opening to give (35) is common with unhindered bases (Section 5.05.3.4). (c) a-Elimination to give a carbene or carbenoid (36) is favored by alkyllithium bases and... 

Finally, a reaction that clearly shows the electrophihc carbenoid-type character of a-lithiated epoxides is the reductive alkylation discovered by CrandaU and Apparu. The transformation is illustrated by the treatment of f-butyl ethylene oxide with t-butyllithium to yield ii-di-f-butylethene (equation 55). The overall reaction results in a conversion of an oxirane into an aUcene under simultaneous substitution of an a-hydrogen atom by the alkyllithium reagent ... 

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