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

Research output: Contribution to journal › Article

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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Gelardi, G., Barker, G., O'Brien, P., & Blakemore, D. C. (2013). Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C. Organic Letters, 15(21), 5424-5427. https://doi.org/10.1021/ol402395j

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AU - Gelardi, Giacomo

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AU - Blakemore, David C.

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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.

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