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Abstract An organocatalytic enantioselective reaction utilizing α‐4‐(4‐hydroxyphenyl)phenylpropargyl alcohols and 3‐substituted indoles has been successfully established for the synthesis of chiral 3 H ‐pyrrolo1,2‐ a indoles. Through the assistance of an appropriate chiral phosphoric acid, a cascade sequence is facilitated, beginning with the dehydration of α‐4‐(4‐hydroxyphenyl)phenylpropargyl alcohols to form alkynyl 4,4’‐biphenyl quinone methides ( 4,4’‐BQMs ). Subsequently, 1,12‐addition of 3 H ‐pyrrolo1,2‐ a indoles to these alkynyl 4,4’‐BQMs results in the formation of allenes, which are then protonated and regenerate 4,4’‐BQMs . Finally, an enantioselective intramolecular annulation of 4,4’‐BQMs occurs smoothly, leading to the production of a range of 3 H ‐pyrrolo1,2‐ a indoles with high efficiency and asymmetric induction.
Pan et al. (Wed,) studied this question.