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Abstract The gold‐catalyzed cycloisomerization of various α‐aminoallenes affords the corresponding 3‐pyrrolines in good to high chemical yields and – if the amino group is unprotected – with complete axis‐to‐center chirality transfer. Diminished levels of chirality transfer were observed in cases of N ‐protected substrates, which may be the result of partial epimerization of the allene in the presence of the gold precatalyst. The low reactivity of the intramolecular hydroamination of unprotected α‐aminoallenes with AuCl 3 was improved by use of gold(I) halides as the precatalyst. Mechanistic studies suggest that a gold(I) compound (formed by oxidation of the aminoallene) is the catalytically active species even if the reaction is started with a gold(III) precatalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Morita et al. (Thu,) studied this question.