Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C

Giacomo Gelardi; Graeme Barker; Peter O'Brien; David C. Blakemore

doi:10.1021/ol402395j

Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C

Giacomo Gelardi, Graeme Barker, Peter O'Brien, David C. Blakemore

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23 Citations (Scopus)

Abstract

The asymmetric lithiation trapping of N-Boc heterocycles using s-BuLi/chiral diamines at temperatures up to −20 °C is reported. Depending on the N-Boc heterocycle, lithiation is accomplished using s-BuLi and (−)-sparteine or the (+)-sparteine surrogate in the temperature range −50 to −20 °C for short reaction times (2–20 min). Subsequent electrophilic trapping or transmetalation–Negishi coupling delivered functionalized N-Boc heterocycles in 47–95% yield and 77:23–93:7 er. With N-Boc pyrrolidine, trapped products can be generated in ∼90:10 er even at −20 °C.

Original language	English
Pages (from-to)	5424-5427
Number of pages	4
Journal	Organic Letters
Volume	15
Issue number	21
Early online date	15 Oct 2013
DOIs	https://doi.org/10.1021/ol402395j
Publication status	Published - 1 Nov 2013

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title = "Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C",

abstract = "The asymmetric lithiation trapping of N-Boc heterocycles using s-BuLi/chiral diamines at temperatures up to −20 °C is reported. Depending on the N-Boc heterocycle, lithiation is accomplished using s-BuLi and (−)-sparteine or the (+)-sparteine surrogate in the temperature range −50 to −20 °C for short reaction times (2–20 min). Subsequent electrophilic trapping or transmetalation–Negishi coupling delivered functionalized N-Boc heterocycles in 47–95% yield and 77:23–93:7 er. With N-Boc pyrrolidine, trapped products can be generated in ∼90:10 er even at −20 °C.",

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T1 - Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C

AU - Gelardi, Giacomo

AU - Barker, Graeme

AU - O'Brien, Peter

AU - Blakemore, David C.

PY - 2013/11/1

Y1 - 2013/11/1

N2 - The asymmetric lithiation trapping of N-Boc heterocycles using s-BuLi/chiral diamines at temperatures up to −20 °C is reported. Depending on the N-Boc heterocycle, lithiation is accomplished using s-BuLi and (−)-sparteine or the (+)-sparteine surrogate in the temperature range −50 to −20 °C for short reaction times (2–20 min). Subsequent electrophilic trapping or transmetalation–Negishi coupling delivered functionalized N-Boc heterocycles in 47–95% yield and 77:23–93:7 er. With N-Boc pyrrolidine, trapped products can be generated in ∼90:10 er even at −20 °C.

AB - The asymmetric lithiation trapping of N-Boc heterocycles using s-BuLi/chiral diamines at temperatures up to −20 °C is reported. Depending on the N-Boc heterocycle, lithiation is accomplished using s-BuLi and (−)-sparteine or the (+)-sparteine surrogate in the temperature range −50 to −20 °C for short reaction times (2–20 min). Subsequent electrophilic trapping or transmetalation–Negishi coupling delivered functionalized N-Boc heterocycles in 47–95% yield and 77:23–93:7 er. With N-Boc pyrrolidine, trapped products can be generated in ∼90:10 er even at −20 °C.

U2 - 10.1021/ol402395j

DO - 10.1021/ol402395j

M3 - Article

C2 - 24180685

VL - 15

SP - 5424

EP - 5427

JO - Organic Letters

JF - Organic Letters

SN - 1523-7060

IS - 21

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