Question

Wittig Reaction Provide a mechanism for the formation of CO2 from bis(2-carbopentyloxy-3,5,6-trichlorophenyl)oxalate.

Wittig Reaction

Provide a mechanism for the formation of CO2 from bis(2-carbopentyloxy-3,5,6-trichlorophenyl)oxalate.

Homework Answers

Answer #1

Negatively charged carbon phosphorus ylide (1) can act as a nucleophile attacking the carbonyl and (2). This leads to betaine (3), which is a type of zwitterion species. This rapidly forms the heterocycle charge separation without giving rise to oxaphosphetane (4). To what extent then the reaction evolves in concert (a) or via an intermediate (b) by the zwitterionic form (5) will condition the final stereoselectivity. Stability triphenylphosphine oxide (7) drives the reaction to yield the alkene product (6).

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