1609976-06-8Relevant articles and documents
Catalytic asymmetric formal [3+3] cycloaddition of an azomethine ylide with 3-indolylmethanol: Enantioselective construction of a six-membered piperidine framework
Shi, Feng,Zhu, Ren-Yi,Dai, Wei,Wang, Cong-Shuai,Tu, Shu-Jiang
, p. 2597 - 2604 (2014)
A catalytic asymmetric formal [3+3] cycloaddition of 3-indolylmethanol and an in situ-generated azomethine ylide has been established to construct a chiral six-membered piperidine framework with two stereogenic centers. This approach not only represents the first enantioselective cycloaddition of isatin-derived 3-indolylmethanol, but also has realized an unusual enantioselective formal [3+3] cycloaddition of azomethine ylide rather than its common [3+2] cycloadditions. Besides, this protocol combines the merits of a multicomponent reaction and organocatalysis, which efficiently assembles a variety of isatin-derived 3-indolylmethanols, aldehydes, and amino esters into structurally diverse spiro[indoline-3,4′-pyridoindoles] with one all-carbon quaternary stereogenic center in high yields and excellent enantioselectivities (up to 93 % yield, >99 % enantiomeric excess (ee)). Although the diastereoselectivity of the reaction is generally moderate, most of the diastereomers can be separated by using column chromatography followed by preparative TLC. An unusual addition: The first catalytic asymmetric formal [3+3] cycloaddition of isatin-derived 3-indolylmethanol with an in situ-generated azomethine ylide has been established to construct a chiral six-membered piperidine framework with two stereogenic centers. This approach represents the first enantioselective cycloaddition of isatin-derived 3-indolylmethanol, and it has realized an unusual enantioselective formal [3+3] cycloaddition of the azomethine ylide (DCEa =a 1,2-dichloroethane). Copyright