Coşkun N, Ma J, Azimi S, Gärtner C, Erden I. 1,2-Dihydropentalenes from fulvenes by [6 + 2] cycloadditions with 1-isopropenylpyrrolidine.
Org Lett 2011;
13:5952-5. [PMID:
22029269 DOI:
10.1021/ol202222d]
[Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In situ generated acetone pyrrolidine enamine undergoes [6 + 2] cycloadditions with fulvenes to give 1,2-dihydropentalenes. This ring annulation method works particularly well with 6-monosubstituted fulvenes and is subject to steric hindrance at C-6 of the fulvene. On the basis of mechanistic studies, optimal conditions have been developed for a one-pot synthesis of 1,2-dihydropentalenes using catalytic amounts of pyrrolidine.
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