Allenes in Catalytic Asymmetric Synthesis and Natural Product Syntheses

Allenes are the simplest class of cumulenes, with two contiguous C=C bonds, and show unique physical and chemical properties. These features make allenes particularly attractive in modern organic chemistry. In this Review, attention is paid to the advances made in catalytic asymmetric synthesis and natural product syntheses based on well-established reactions of allenes, such as propargylation, addition, cycloaddition, cycloisomerization, cyclization, etc., with or without catalysts. Their versatile reactivity, substituent-loading ability, axial to center chirality transfer, and controllable selectivity allow access to target molecules by unique and efficient approaches. The main topics in this Review are presented with selected examples from 2003 to 2011. Creative and easy syntheses of chiral compounds and natural products are possible by using allenes. These compounds display exceptional physical and chemical properties, and thus offer new possibilities in catalytic asymmetric synthesis and the total synthesis of natural products. The remarkable progress made in these two topics is summarized selectively in this Review. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.