Synthesis of highly functionalized enantiopure halocyclopropanes derived from carbohydrates

A chromium-mediated synthesis of enantiopure sugar-based halocyclopropanecarboxamides is reported. This reaction can be stereospecifically carried out on (E)- or (Z)-¿,ß-unsaturated amides and takes place with the formation of a new C-Hal stereogenic center, which is generated with total stereoselectivity. Synthetic applications of the obtained halocyclopropanecarboxamides are also reported. The structure of the halocyclopropanes and derivatives were established by X-ray analysis. A mechanism to explain these transformations is proposed. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
The authors acknowledge financial support from the Spanish Ministerio de Economía y Competitividad (MINECO) (grant numbers CTQ2010-14959, MAT2006-01997, MAT2010-15094 and Factoria de Cristalización Consolider Ingenio 2010), the Portuguese Fundação para a Ciencia e a Tecnologia (FCT), the European Union (EU), Quadro de Referência Estratégico Nacional (QREN), Fundo Europeu de Desenvolvimento Regional (FEDER) and Programa Operacional Temático Factores de Competitividade (COMPETE) (project PEst-C/QUI/UI0062/2011). C. C. and V. d. A. thank the Ministerio de Ciencia e Innovación (MICINN) for a Juan de la Cierva and Ramón y Cajal contract. A. D. P. thanks the Universidad de Oviedo for a predoctoral fellowship, and R. S. thanks the FCT for an “Investigador Auxiliar” position.