Organolithium reagents, reaction with epoxides

The reaction of epoxides and nucleophiles was introduced in Chapter 11 (Section 11.8.2). Grignard reagents and organolithium reagents react with epoxides at the less sterically hindered carbon atom. The reaction of phenylmagnesium bromide and epoxide 33, for example, generates alkoxide 34. An aqueous acid workup converts the alkoxide to the conjugate acid and final product, alcohol 35. 

Epoxides are opened with organolithium reagents, normally with attack at the less-substituted carbon atom of the epoxide. A potential competing reaction is proton abstraction adjacent to the epoxide, leading to an allylic alcohol. 

FIGURE 14.56 Preparation of Grignard and organolithium reagents and their reactions with epoxides. 

Scheme 4.67. Reaction of epoxides with organolithium and Grignard reagents[296, 310-313].

Write equations for the reaction of organolithium reagents with water or epoxides. 

Mechanism 14-4 Base-Catalyzed Opening of Epoxides 653 14-14 Orientation of Epoxide Ring Opening 654 14-15 Reactions of Epoxides with Grignard and Organolithium Reagents 656 14-16 Epoxy Resins The Advent of Modern Glues 656 Summary Reactions of Epoxides 658 EssentialTerms 660 Study Problems 662... 

Reactions of Epoxides with Grignard and Organolithium Reagents... 

The a-halo carbonyl compounds are reagents for the synthon +C-C=0. At a lower oxidation level, epoxides are reagents for the synthons +C-C=0 as in their reaction with Grignard or organolithium reagents (see also frames 162-6). 

The nucleophilic carbon of an organometallic compound reacts with an electrophile. For example, in the following reactions, the organolithium reagent and the Grignard reagent each react with an epoxide. 

There are limited data on 1,2-epoxy of glycal epoxide ring opening reaction with C-nucleophiles other than organocuprate, e.g., Grignard reagents [217, 218], organolithium compounds [217-219], aUylstannane [217], and sodio di-tert-butyl malonate [219, 220]. 

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