Asymmetric reactions Nicholas reaction

Modifications to the standard Nicholas reaction generally fall into the following categories asymmetric reactions, use of heteroatom nucleophiles, use of metals other than cobalt, reactions of neutral electrophiles, reactions of carbocations not in the a-position, cycloadditions, and rearrangements. 

In addition to her studies on the asymmetric Nicholas reaction mentioned previously (13 14), Tyrrell investigated standard intramolecular cyclizations to generate benzopyrans. An important advance in this report is that Tyrrell performed the cobalt complexation, Nicholas reaction, and cobalt decomplexation using a one-pot procedure. The conversion of propargyl alcohol 48 into benzopyran 49 highlights this strategy... 

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