A phosphine-catalyzed approach to pyrrolines has been developed that involves two mechanistically unlinked catalytic processes. The first involves the redox isomerization of amino crotonates to provide access to aliphatic tosyl imines, which then engage in a (3+2) annulation with various allenoates. The reaction shows generality, with 24 examples established, along with a low yielding and moderately enantioselective variant. Mechanistic studies indicate that the viability of the process is linked to the selection of catalysts with similar propensity to add to the two coupling partners.
Bibliographical noteFunding Information:
The authors thank the Australian Research Council through the Discovery (DP200101448) and Laureate (FL170100041) programs for financial support, and the National Computational Infrastructure for supercomputing time.
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- phosphine catalysis
- redox isomerization
- tandem catalysis