The Pummerer rearrangement has been applied extensively in the formation of new carbon-carbon or carbon-heteroatom bonds since its discovery in 1909. While it is compatible with a broad range of nucleophiles, phosphines have previously been unusable as nucleophiles due to the propensity of competing redox chemistry with sulfoxides. Here we report a simple procedure that circumvents this problem and facilitates formal phosphine Pummerer reactions. This method is employed in the preparation of thioalkyl phosphonium salts which gives rise to a wide range of vinyl sulfides via Wittig olefination chemistry with aldehydes. Subsequent hydrolysis of these vinyl sulfides under mild conditions offers an efficient and versatile two-step one-carbon homologation of aldehydes to ketones. This presentation will detail our discovery, development, and scope of this chemistry and highlight related method development that is ongoing in our lab.

Improved access to thioalkyl phosphonium salts enables a two-step homologation of aldehydes to ketones

ACS Spring 2022

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