Intramolecular activation of ortho-substituted aryl sulfones leading to either homolytic or heterolytic sulfone cleavage under mild conditions
Abstract
A new strategy for the activation of aryl sulfones towards homolytic and heterolytic cleavage via intramolecular reactions with ortho-substituents has been investigated. Utilizing ortho substituents to promote desulfonylation has led to the discovery of a variety of unprecedented modes of aryl sulfone cleavage. Electrophilic silyl species placed ortho to unactivated tertiary sulfones react to form sultinium intermediates which suffer elimination in high yield at room temperature. Stannyl radical species placed ortho to allylic sulfones react to form intermediates which homolytically cleave to afford allyl radicals capable of further intramolecular cyclization reactions. Silylmethylene radicals attached ortho to tertiary sulfones abstract a $\beta$-sulfonyl hydrogen resulting in radical elimination of the sulfone and olefin formation. Addition of tris(trimethylsilyl)silyl radicals to ortho-allyldimethylsilyl aryl sulfones results in the formation of $\beta$-silyl radicals which promote homolytic sulfone cleavage to afford tertiary and secondary alkyl radicals. A separate investigation directed towards the functionalization of 1H-perfluoroalkanes led to the discovery that deprotonation of 1H-perfluoroalkanes at $-$110$\sp\circ$ to $-$115$\sp\circ$C followed by a CO$\sb2$ or SO$\sb2$ quench minimized interference from $\beta$-fluoride elimination and afforded perfluoroalkyl carboxylates and sulfinates in moderate to good yield.
Degree
Ph.D.
Advisors
Fuchs, Purdue University.
Subject Area
Organic chemistry
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.