Kurt Spellmeyer Responds

Spellmeyer, Kurt

doi:10.2307/377764

Cited by 1 publication

(2 citation statements)

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“…A 5-exo-trig cyclization of I was proposed to lead to II. Theoretical studies described by Houk and Spellmeyer 244 support the observed regio-and chemoselectivity of this cyclization, indicating a ≥4.2 kcal/mol preference for this pathway over alternative cyclization pathways. The formation of radical intermediate IV was proposed to result from 5-exo-dig cyclization of intermediate III instead of II, as calculations predicted that it was energetically more favorable by ~4 kcal/mol.…”

Section: Synthesis Of Natural Productssupporting

confidence: 56%

“…The preference for 6-exo-trig, as opposed to 7-endotrig, cyclization is consistent with previous work involving the intramolecular addition to an alkene via a carbon radical. 192 A switch in regioselectivity was achieved by replacing the H at R 3 with Me or Br (602). The nonallylic radical in 605 is tertiary (when R 3 = Me) and gains extra stability from hyperconjugation and kinetic stability from steric hindrance.…”

Section: Withmentioning

confidence: 99%

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Mechanistic Aspects and Synthetic Applications of Radical Additions to Allenes

2019

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More than 50 years have passed since Haszeldine reported the first addition of a trifluoromethyl radical to an allene; in the intervening years, both the chemistry of allenes and the reactivity of single-electron species have become topics of intense interest. In this Review, we provide an overview of the fundamentals of radical additions to allenes and highlight the emergence of theoretical and experimental evidence that reveals unique reactivity patterns for radical additions to allenes as compared with other unsaturated compounds. Factors capable of exerting control over the chemo-, regio-, and stereoselectivities of the attack of carbon-and heteroatom-based radicals at each of the three potential reactive sites in an allene substrate are described. These include reaction conditions, the nature of the attacking radical, the substitution pattern of the allene, and the length of the linker between the radical center and the proximal allene carbon in the substrate. Cycloaddition reactions between allenes and partners containing π-bonds, which are likely to proceed through radical pathways, are presented to highlight their ability to rapidly access complex polycyclic scaffolds. Finally, the synthetic utility of the products arising from these chemistries is described, including their applications to the construction of complex molecules.

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Section: Synthesis Of Natural Productssupporting

confidence: 56%

Section: Withmentioning

confidence: 99%