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 journalArticle

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 languageEnglish
Pages (from-to)5424-5427
Number of pages4
JournalOrganic Letters
Volume15
Issue number21
Early online date15 Oct 2013
DOIs
Publication statusPublished - 1 Nov 2013

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Sparteine
Temperature
Diamines

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Gelardi, Giacomo ; Barker, Graeme ; O'Brien, Peter ; Blakemore, David C. / Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C. In: Organic Letters. 2013 ; Vol. 15, No. 21. pp. 5424-5427.
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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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Asymmetric Lithiation Trapping of N-Boc Heterocycles at Temperatures above −78 °C. / Gelardi, Giacomo; Barker, Graeme; O'Brien, Peter; Blakemore, David C.

In: Organic Letters, Vol. 15, No. 21, 01.11.2013, p. 5424-5427.

Research output: Contribution to journalArticle

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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

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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.

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