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Lewis Acid-Promoted Enantioselective Dearomative Spirocyclizations of Allenes.

ABSTRACT: A chiral oxazaborolidine combined with SnCl4 has been found to promote the dearomative spirocyclization of electron-rich benzyl allenyl ketones. The reaction outcome is sensitive to the nature of activating acid, which was rationalized using hard-soft acid-base (HSAB) theory. The spirocyclic product was obtained with up to 72% ee, which is the best result reported to date for these substrates. The formation of cross-conjugated or conjugated products is readily controlled by changing the oxygen-protecting groups.

SUBMITTER: Tcyrulnikov S

PROVIDER: S-EPMC6173636 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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Lewis Acid-Promoted Enantioselective Dearomative Spirocyclizations of Allenes.

Tcyrulnikov Sergei S Curto John M JM Gilmartin Philip H PH Kozlowski Marisa C MC

The Journal of organic chemistry 20180905 19

A chiral oxazaborolidine combined with SnCl<sub>4</sub> has been found to promote the dearomative spirocyclization of electron-rich benzyl allenyl ketones. The reaction outcome is sensitive to the nature of activating acid, which was rationalized using hard-soft acid-base (HSAB) theory. The spirocyclic product was obtained with up to 72% ee, which is the best result reported to date for these substrates. The formation of cross-conjugated or conjugated products is readily controlled by changing t ...[more]

PMID: 30141933

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