Late-Stage Macrocyclization of Bioactive Peptides with Internal Oxazole Motifs via Palladium-Catalyzed C–H Olefination
作者:Shu Liu、Chuangxu Cai、Zengbing Bai、Wangjian Sheng、Jiantao Tan、Huan Wang
DOI:10.1021/acs.orglett.1c00580
日期:2021.4.16
the synthesis and direct functionalization of complex oxazole-containing peptides are in high demand. Herein, we report the late-stage site-selective functionalization of oxazole-containing peptides viapalladium-catalyzed δ-C(sp2)–H olefination of phenylalanine, tryptophan, and tyrosine residues. This strategy utilizes oxazole motifs as internal directing groups and provides access to oxazole-containing
New carbohydrate-based chiral auxiliaries in Diels–Alder reaction
作者:Maria L.G. Ferreira、Sergio Pinheiro、Clarissa C. Perrone、Paulo R.R. Costa、Vı́tor F. Ferreira
DOI:10.1016/s0957-4166(98)00286-9
日期:1998.8
The carbohydrate derivatives 1–5 were evaluated as chiralauxiliaries in the Diels–Alderreaction of its acrylate derivatives 6a–e with cyclopentadiene promoted by Lewis acids. Although excellent endo:exo ratios (98:2) were obtained in many cases, the π-facial selectivities were from low to moderate (up to 60% d.e.). An effect of non-coordinating solvents reversing the stereoselectivities of adducts
environmentally benign manner. A novel C–OH bond cleavage method was found to be crucial for this practical protocol. A variety of alkenes and allylic alcohols equipped with wide-spectrum functional groups can be successfully incorporated into the desired cross-coupling, affording 1,4-dienes with moderate to excellent yields and high stereo- and regioselectivity.
organic photoredox-catalyzed dehydroxylative trifluoromethylation of allylic alcohols was developed in an environmentally benign manner. In this reaction, the readily available CF3SO2Na was selected as the trifluoromethylation reagent. The in situ generated byproduct SO2 was reutilized to activate C–OH bond, which enabled this dehydroxylative trifluoromethylation to be performed conveniently. A variety
以环境友好的方式开发了有机光氧化还原催化的烯丙醇脱羟基三氟甲基化。本反应选用易得的CF 3 SO 2 Na作为三氟甲基化试剂。在原位通过产品生成SO 2被再利用来激活C-OH键,这使此dehydroxylative三氟甲基化将被方便地进行。以高产率和优异的立体选择性获得了多种多功能化的 CF 3 -烯丙基化合物。