Cu(I)/Rh(II)-Catalyzed Tandem Reaction of 1-Alkynes, Sulfonyl Azides, and Morita-Baylis-Hillman Adducts

Abstract

A novel Cu(I)/Rh(II)-catalyzed tandem reaction of 1-alkynes, sulfonyl azides, and Morita-Baylis-Hillman(MBH) adducts has been investigated. In this catalytic process, the starting molecules could assembled sequentially through the Cu(I)-catalyzed cycloaddition of 1-alkynes with sulfonyl azides affording N-sulfonyl-1,2,3-triazoles, from which α-imino Rh(II)-carbene intermediates can be generated in the presence of Rh(II) catalysts, undergoing 1,3-insertion into the O-H bond of MBH adducts, followed by [3.3]-sigmatropic rearrangement to afford highly functionalized α-methylene-δ-oxo-γ-amino carbonyl compounds in high yields. Through optimization experiments for the Rh(II)-catalyzed reaction of N-sulfonyl-1,2,3-triazoles with ester-functionalized allylic alcohol (acyclic MBH adducts), it has been found that the reaction underwent efficiently in the presence of 2.5 mol % of Rh_(2)(^(t)BuCO_(2))_(4) in toluene (1.0 ml) at 80 ℃ to afford α-methylene-δ-oxo-γ-amino esters. This reaction protocol showed broad substrate scope toward for both triazoles and acyclic MBH adducts. Under the similar reaction conditions, cyclic MBH adducts, α-methyl alcohol cyclopentenone, also effectively reacted. It has also been demonstrated that the tandem all-in-one-pot three component reaction of 1-alkynes, sulfonyl azides, and MBH adducts in the presence of Cu(I) and Rh(II) catalysts can also afford product in high yields.;1-Alkynes과 Sulfonyl Azides, Morita-Baylis-Hillman adduct(이하, MBH)를 이용해, 새로운 Cu(I)와 Rh(II) 촉매 Tandem 합성을 개발했습니다. 이러한 촉매작용 과정에서는 1-alkynes과 sulfonyl azides가 Cu(I) 촉매와 반응하여 Click Chemistry를 통해 N-sulfonyl-1,2,3-triazoles를 만들어냅니다. 다음으로 Rh(II)촉매와 반응하여 α-imino Rh(II)-carbenoid가 만들어집니다. 이는 친전자적인 성질을 띠어서 다양한 친핵체와 반응할 수 있는데, 이번 연구에서는 친핵체로 MBH adduct이라는 알코올 파생물을 이용하였습니다. 이 둘이 반응하여 O-ylide 중간체를 만들어 내고, 열에 의해 [3,3]-sigmatropic rearrangement를 하여 빠르고 높은 수율의 α-methylene-δ-oxo-γ-amino carbonyl compounds을 만들어 낼 수 있었습니다. N-sulfonyl-1,2,3-triazoles과 acyclic MBH adduct가 Rh(II) 촉매 작용하는 최적의 조건을 찾기 위한 실험들이 진행되었고, 80도에서 toluene(1.0 ml)와 2.5 mol%의 Rh_(2)(^(t)BuCO_(2))_(4) 촉매가 사용되었을 때 α-methylene-δ-oxo-γ-amino esters를 가장 효율적으로 만들어냄을 확인하였습니다. 또한, 이 반응은 triazole과 acyclic MBH adduct에 대해 폭넓은 기질 범위를 보여주고 있습니다. 비슷한 반응 조건에서, cyclic MBH adducts (α-methyl alcohol cyclopentenone)를 사용하였을 때 역시 효과적인 반응을 보였습니다. 더 나아가 Cu(I)와 Rh(II) 촉매들이 동시에 작용하여 1-alkynes, sulfonyl azides 그리고 MBH adducts가 이 3가지 구성요소들이 존재하는 tandem all-in-one-pot 반응이 높은 수율을 제공하는 것을 증명하였습니다.