Asymmetric construction of quaternary stereogenic centers via auxiliary-based SN2′ reactions: A case of 1,7-relative stereogenesis

Scott E. Denmark, Lyndon K. Marble

Research output: Contribution to journalArticle

Abstract

The stereoselective construction of quaternary stereogenic centers is described that employs an allylic substitution through the intermediacy of a chiral carbamate leaving group. Five carbamates with two substituents at the allylic terminus combined with phenylcopper or n-butylcopper to provide alkenes in moderate to good yields and with moderate to high enantioselectivities at the newly created quaternary stereogenic center. The E-carbamate with methyl and cyclohexyl substituents at the γ-terminus provided the highest yield (87%) and enantioselectivity (>99.9:0.1 er) of all the substitution patterns tested. The corresponding Z-carbamate gave the lowest enantioselectivity observed (80.0:20.0). Carbamates with other substituents (n-butyl and t-butyl) at the E-terminal position gave moderate yields and enantioselectivities of alkenes. Cinnamyl substrates also provided good yields of alkenes with moderate enantioselectivities. The origin of enantioselectivity is analyzed in the context of dimeric lithioheterocuprate structures.

Original languageEnglish (US)
Pages (from-to)559-590
Number of pages32
JournalHeterocycles
Volume88
Issue number1
DOIs
StatePublished - Jan 1 2014

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Carbamates
Enantioselectivity
Alkenes
Substitution reactions
Substrates

ASJC Scopus subject areas

  • Analytical Chemistry
  • Pharmacology
  • Organic Chemistry

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Asymmetric construction of quaternary stereogenic centers via auxiliary-based SN2′ reactions : A case of 1,7-relative stereogenesis. / Denmark, Scott E.; Marble, Lyndon K.

In: Heterocycles, Vol. 88, No. 1, 01.01.2014, p. 559-590.

Research output: Contribution to journalArticle

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