3727-53-5Relevant articles and documents
Strain-Driven Dyotropic Rearrangement: A Unified Ring-Expansion Approach to α-Methylene-γ-butyrolactones
Lei, Xiaoqiang,Li, Yuanhe,Lai, Yang,Hu, Shengkun,Qi, Chen,Wang, Gelin,Tang, Yefeng
supporting information, p. 4221 - 4230 (2020/12/22)
An unprecedented strain-driven dyotropic rearrangement of α-methylene-β-lactones has been realized, which enables the efficient access of a wide range of α-methylene-γ-butyrolactones displaying remarkable structural diversity. Several appealing features of the reaction, including excellent efficiency, high stereospecificity, predictable chemoselectivity and broad substrate scope, render it a powerful tool for the synthesis of MBL-containing molecules of either natural or synthetic origin. Both experimental and computational evidences suggest that the new variant of dyotropic rearrangements proceed in a dualistic pattern: while an asynchronous concerted mechanism most likely accounts for the reactions featuring hydrogen migration, a stepwise process involving a phenonium ion intermediate is favored in the cases of aryl migration. The great synthetic potential of the title reaction is exemplified by its application to the efficient construction of several natural products and relevant scaffolds.
Synthesis of bicyclic γ-butyrolactone derivatives by rhodium catalyzed intramolecular C-H insertion of α-dizao α-phosphoryl cycloalkyl esters
Shie, Jr-Yun,Zhu, Jia-Liang
, p. 1590 - 1601 (2016/03/01)
Under the catalysis of Rh2(OAc)4, several readily prepared cycloalkyl α-diazo α-phosphoryl esters undergo a intramolecular C-H insertion reaction to afford the fused bicyclic α-phosphoryl-γ-butyrolactones in varying yields (10%-80%) and dr ratios (69:14:17 to >99:1). The experimental results reveal that the reactivity of the precursors and the diastereoselectivity of the cyclization are both influenced by the ring sizes of the cycloalkyl moieties. Moreover, most of the resulting products can be further elaborated into α,α-dialkyl γ-butyrolactones via a two-step alkylation/reductive alkylation sequence with the controlled installation of two alkyl groups to the lactones. In addition, application of Horner-Wadsworth-Emmons (HWE) olefination reaction to the insertion products allows an access to bicyclic α-alkylidene-γ-butyrolactone ring systems that occur ubiquitously in biologically active natural products and synthetic molecules.
Dibromomethane as one-carbon source in organic synthesis: A versatile methodology to prepare the cyclic and acyclic α-methylene or α-keto acid derivatives from the corresponding terminal alkenes
Hon, Yung-Son,Liu, Yu-Wei,Hsieh, Cheng-Han
, p. 4837 - 4860 (2007/10/03)
Ozonolysis of mono-substituted alkenes A-1 followed by reacting with a preheated mixture of CH2Br2-Et2NH affords α-substituted acroleins A-2 in good yields. Under very mild reaction conditions, these α-substituted acroleins A-2 can be easily converted to α-methylene esters A-4, which could be further converted to the corresponding α-keto esters A-5. This methodology can be also applied to the preparation of α-methylene lactones B-4, α-methylene lactams, and α-keto lactones B-5 with various ring sizes.
