Stereogenic propargylic centers via base-mediated terminal allne isomerization

John D. Spence; Justin K. Wyatt; Daniel M. Bender; David K. Moss; Michael H. Nantz

Stereogenic propargylic centers via base-mediated terminal allne isomerization

John D. Spence, Justin K. Wyatt, Daniel M. Bender, David K. Moss, Michael H. Nantz

Chemistry

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12 Scopus citations

Abstract

A study of alkali metal amide-mediated isomerizations of terminal allenes is described. The isomerizations of substituted ethenylidenecyclohexanes to form diastereomeric mixtures of terminal alkynes have been conducted to determine factors which may influence the stereochemistry at the newly formed propargylic centers. An initial base screen revealed that potassium N-methylbutylamide (KMBA) exhibits the highest level of equatorial to axial alkyne diastereoselectivity. With the severely hindered terminal allene 26, the use of potassium 3-aminopropylamide is required to effect isomerization. A general synthesis of deuterated terminal allenes has also been achieved, and a mechanistic study using d₂-allenes 18a,b has revealed the involvement of a propargylic anion in the course of the KMBA-mediated isomerizations.

Original language	English (US)
Pages (from-to)	4014-4021
Number of pages	8
Journal	Journal of Organic Chemistry
Volume	61
Issue number	12
State	Published - Jun 14 1996

ASJC Scopus subject areas

Organic Chemistry

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title = "Stereogenic propargylic centers via base-mediated terminal allne isomerization",

abstract = "A study of alkali metal amide-mediated isomerizations of terminal allenes is described. The isomerizations of substituted ethenylidenecyclohexanes to form diastereomeric mixtures of terminal alkynes have been conducted to determine factors which may influence the stereochemistry at the newly formed propargylic centers. An initial base screen revealed that potassium N-methylbutylamide (KMBA) exhibits the highest level of equatorial to axial alkyne diastereoselectivity. With the severely hindered terminal allene 26, the use of potassium 3-aminopropylamide is required to effect isomerization. A general synthesis of deuterated terminal allenes has also been achieved, and a mechanistic study using d2-allenes 18a,b has revealed the involvement of a propargylic anion in the course of the KMBA-mediated isomerizations.",

author = "Spence, {John D.} and Wyatt, {Justin K.} and Bender, {Daniel M.} and Moss, {David K.} and Nantz, {Michael H.}",

year = "1996",

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language = "English (US)",

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pages = "4014--4021",

journal = "Journal of Organic Chemistry",

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T1 - Stereogenic propargylic centers via base-mediated terminal allne isomerization

AU - Spence, John D.

AU - Wyatt, Justin K.

AU - Bender, Daniel M.

AU - Moss, David K.

AU - Nantz, Michael H.

PY - 1996/6/14

Y1 - 1996/6/14

N2 - A study of alkali metal amide-mediated isomerizations of terminal allenes is described. The isomerizations of substituted ethenylidenecyclohexanes to form diastereomeric mixtures of terminal alkynes have been conducted to determine factors which may influence the stereochemistry at the newly formed propargylic centers. An initial base screen revealed that potassium N-methylbutylamide (KMBA) exhibits the highest level of equatorial to axial alkyne diastereoselectivity. With the severely hindered terminal allene 26, the use of potassium 3-aminopropylamide is required to effect isomerization. A general synthesis of deuterated terminal allenes has also been achieved, and a mechanistic study using d2-allenes 18a,b has revealed the involvement of a propargylic anion in the course of the KMBA-mediated isomerizations.

AB - A study of alkali metal amide-mediated isomerizations of terminal allenes is described. The isomerizations of substituted ethenylidenecyclohexanes to form diastereomeric mixtures of terminal alkynes have been conducted to determine factors which may influence the stereochemistry at the newly formed propargylic centers. An initial base screen revealed that potassium N-methylbutylamide (KMBA) exhibits the highest level of equatorial to axial alkyne diastereoselectivity. With the severely hindered terminal allene 26, the use of potassium 3-aminopropylamide is required to effect isomerization. A general synthesis of deuterated terminal allenes has also been achieved, and a mechanistic study using d2-allenes 18a,b has revealed the involvement of a propargylic anion in the course of the KMBA-mediated isomerizations.

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