DUGi

Chiral Induction in Intramolecular Rhodium-Catalyzed [2+2+2] Cycloadditions of Optically Active Allene-ene/yne-allene Substrates

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@2072@@298897

Allene-yne-allene and allene-ene-allene N-tosyl-linked substrates with two chiral centres in the α-position of the allene moiety were satisfactorily prepared starting both from racemic and chiral propargylic alcohols. The Wilkinson’s complex-catalyzed [2+2+2] cycloaddition reaction of these substrates was evaluated. In the case of enantiomerically pure bisallenes, high stereoselectivity was observed, giving a diastereomerically pure cycloadduct. The chirality of starting bisallene substrates can be completely transferred to the cycloadducts, representing an atom-economical and enantiospecific process for the construction of fused polycycles. However, when reacting an oxygen-linked allene-ene-allene substrate, the stereoselectivity decreased and two diastereoisomers were formed. A detailed characterization study of the resulting cycloadducts allowed us to identify the enantioisomer generated in the cycloaddition

Financial support from the Spanish Ministry of Education and Science (MINECO) (Projects No.: CTQ2014–54306-P, CTQ2015-64436-P and SAF2014-52223-C2-1-R) and the DIUE of the Generalitat de Catalunya (Project No.: 2014SGR931 and predoctoral grant to M.F.) are acknowledged. Thanks are due to UdG for a predoctoral grant to E.H.

Wiley