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Synthetic and Computational Study of Tin-Free Reductive Tandem Cyclizations of Neutral Aminyl Radicals.

ABSTRACT: 5- exo, 5- exo Cyclizations of conformationally unbiased propargylic aminyl radicals proceed with excellent yield, chemoselectivity, and diastereoselectivity under tin-free reductive cyclization conditions, regardless of the electronic environments and intermediate radical stabilization resulting from various olefin substituents. These conditions avoid the need for slow addition of initiator and reductant. By contrast, analogous 6- exo, 5- exo cyclizations require substituents capable of intermediate radical stabilization to avoid premature reduction products. These experimental results are corroborated by computations that further establish the reactivity of these aminyl radicals upon exposure to tin-free cyclization conditions.

SUBMITTER: Sirinimal HS

PROVIDER: S-EPMC6261332 | biostudies-other | 2018 Oct

REPOSITORIES: biostudies-other

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Synthetic and Computational Study of Tin-Free Reductive Tandem Cyclizations of Neutral Aminyl Radicals.

Sirinimal Hansamali S HS Hebert Sebastien P SP Samala Ganesh G Chen Heng H Rosenhauer Gregory J GJ Schlegel H Bernhard HB Stockdill Jennifer L JL

Organic letters 20180928 20

5- exo, 5- exo Cyclizations of conformationally unbiased propargylic aminyl radicals proceed with excellent yield, chemoselectivity, and diastereoselectivity under tin-free reductive cyclization conditions, regardless of the electronic environments and intermediate radical stabilization resulting from various olefin substituents. These conditions avoid the need for slow addition of initiator and reductant. By contrast, analogous 6- exo, 5- exo cyclizations require substituents capable of interme ...[more]

PMID: 30265551

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