Manganese-catalyzed cyclopropanation of allylic alcohols with sulfones
Ke Yu, Qin Nie, Qianjin Chen, Weiping Liu
Abstract
Cyclopropanes are among the most important structural units in natural products, pharmaceuticals, and agrochemicals. Herein, we report a manganese-catalyzed cyclopropanation of allylic alcohols with sulfones as carbene alternative precursors via a borrowing hydrogen strategy under mild conditions. Various allylic alcohols and arylmethyl trifluoromethyl sulfones work efficiently in this borrowing hydrogen transformation and thereby deliver the corresponding cyclopropylmethanol products in 58% to 99% yields. Importantly, a major benefit of this transformation is that the versatile free alcohol moiety is retained in the resultant products, which can undergo a wide range of downstream transformations to provide access to a series of functional molecules. Mechanistic studies support a sequential reaction mechanism that involves catalytic dehydrogenation, Michael addition, cyclization, and catalytic hydrogenation. Developing readily available and bench-stable reagents for the cyclopropanation of olefins is needed as traditional methodologies mainly rely on carbene-based strategies. Herein, the authors report a manganese-catalyzed cyclopropanation of allylic alcohols with sulfones via a borrowing hydrogen strategy under mild conditions.