Utilizing Silicon Chemistry: A Greener Approach for Achieving Regioselective Wittig Rearrangements and [1,2]-Carbon to Carbon Silyl Migration

The Wittig rearrangements ([2,3], [1,2] and [1,4]) are a pivotal synthetic strategy for forming carbon-carbon bonds. Despite extensive documentation of the [2,3]-Wittig, the questions related to the regioselective pathways of the [1,2] and [1,4]-Wittig rearrangements remain unanswered. Furthermore, it is unclear whether the [1,4]-Wittig occurs via a concerted or stepwise mechanism is unclear. The [1,4]-Wittig also has a limited substrate scope. Addressing these uncertainties could significantly enhance the applicability and predictive power of this transformation within synthetic organic methodology.

Tin-lithium exchange provided regioselectivity in Wittig rearrangements, but tin’s toxicity led to a search for other materials. Our prior research has demonstrated that directed carbanion generation through silicon-lithium exchange or α deprotonation to silicon significantly enhances regioselectivity in Wittig rearrangements. Therefore, it is a greener approach to Wittig rearrangements. Recently, an atom economical route for accessing α silyl alkanals has been developed using [1,2]-Carbon to carbon silyl migration chemistry.