通過給氫鍵配體實現鈀-氧雜烯丙基的手性逆電子需求(3+2)環加成反應
作者:
小柯機器人發布時間:2021/1/12 16:53:55
近日,南開大學的資偉偉課題組通過給氫鍵配體實現了鈀-氧雜烯丙基的手性逆電子需求(3+2)環加成反應。該項研究成果發表在2021年1月6日出版的《美國化學會志》上。
研究人員報導了一種對映選擇性(3+2)環加成反應,該反應發生在鈀-氧雜烯丙基和缺電子的硝基烯之間。該反應是通過一個理性設計的給氫鍵配體(FeUrPhos)、以逆電子需求的通路發生的。利用這一方法,研究人員可以構建多達三個連續手性中心的環戊酮類分子,且對映和非對映選擇性都很高。
據介紹,氧雜烯丙基陽離子與烯烴之間的環加成反應是構建環系統的重要途徑。雖然氧雜烯丙基陽離子的(4+3)環加成反應已較為成熟,其(3+2)環加成反應依舊較為罕見,且之前尚未有其非對稱版本的報導。此外,由於氧雜烯丙基陽離子高度親電,只有富電子的烯烴可被用作環加成對象。
附:英文原文
Title: Enantioselective Inverse Electron Demand (3 + 2) Cycloaddition of Palladium-Oxyallyl Enabled by a Hydrogen-Bond-Donating Ligand
Author: Yin Zheng, Tianzhu Qin, Weiwei Zi
Issue&Volume: January 6, 2021
Abstract: Cycloaddition reactions between oxyallyl cations and alkenes are important transformations for the construction of ring systems. Although (4 + 3) cycloaddition reactions of oxyallyl cations are well-developed, (3 + 2) cycloadditions remain rare, and an asymmetric version has not yet been developed. Moreover, because oxyallyl cations are highly electrophilic, only electron-rich olefins can be used as cycloaddition partners. We herein report a method for enantioselective (3 + 2) cycloaddition reactions between palladium-oxyallyl species and electron-deficient nitroalkenes. This transformation was enabled by a rationally designed hydrogen-bond-donating ligand (FeUrPhos) and proceeded via an inverse electron demand pathway. Using this method, we could assemble cyclopentanones with up to three contiguous stereocenters with high enantioselectivity and good to excellent diastereoselectivity.
DOI: 10.1021/jacs.0c11504
Source: https://pubs.acs.org/doi/10.1021/jacs.0c11504