A Mild and Efficient Approach to Novel Tetrasubstituted Allenes Featuring Sulfoxonium Ylide Motifs

In this work, we describe the synthesis of tetrasubstituted allenes (3a–m) from keto-sulfoxonium ylides (2a–h) and propargylic alcohols (1a–d) under mild reaction conditions. Sulfoxonium ylides act as carbene precursors and can also undergo a variety of transformations owing to their amphiphilic nature, making them versatile tools for the development of new synthetic methodologies.^{1, 2, 3}

Allenes, in turn, constitute a unique class of compounds featuring orthogonal π-systems, which confer distinct structural and electronic properties. The synthesis and functionalization of highly substituted allenes remain challenging, particularly due to issues associated with regioselectivity.

To the best of our knowledge, this work represents the first report describing the synthesis of sulfoxonium ylides bearing an allene moiety in their structure. Moreover, the resulting allene–ylides (3) constitute versatile synthetic intermediates, enabling the preparation of a wide range of structurally diverse and more complex allenes from a single molecular platform.