α-Methylene-β-lactams 3 were synthesized from the various 2-bromoallylamine derivatives 2 using a catalytic amount of Pd(OAc)2 or PD(acac)2 and PPh3, under 1–4 atom pressure of CO in good yields. Similarly, α-alkylidene-β-lactams 20 were synthesized from 3-alkyl-2-bromoallylamines 19, which were easily prepared from the olefins 14, in the same manner.
A Simple and Efficient Protocol to 1,2,4-Substituted Pyrroles via a Sonogashira Coupling-Acid-Catalyzed Cyclization
作者:Hongwei Zhou、Da Zhu、Jie Zhao、Yuxiu Wei
DOI:10.1055/s-0030-1261175
日期:2011.9
A facile and efficient protocol for the synthesis of 1,2,4-substituted pyrrole derivatives was developed. As a result of the ready availability of materials and the simple operation, this type of reaction should have potential utility in organic synthesis.
A novel synthesis of oxazolidin-2-ones by carbamic acid formation and a subsequent copper-catalyzed intramolecular vinylation from N-(2-bromoallyl)amines and KHCO3 was developed. KHCO3 was used as a C1 source and base in this efficient and convenient cascade process.
Neighbouring-group Influence on the Ring Opening of 2-Aryloxymethyl-1,1,2-tribromocyclopropanes under Phase-transfer Conditions.
作者:Einar Bakstad、Are S. Olsen、Marcel Sandberg、Leiv K. Sydnes、Bengt Långström、Shi-Ping Yan、Geng-Lin Wang、Xin-Kan Yao、Hong-Gen Wang、J. -P. Tuchagues、Mattias Ögren
DOI:10.3891/acta.chem.scand.53-0465
日期:——
When a number of 2-aryloxymethyl-1,1,2-tribromocyclopropa were treated with sodium hydroxide and ethanol under phase-transfer conditions, ring opening occurred to give mixtures of acetylenic diethyl acetals and ketals in better than 80% total isolated yield. The acetylenic diethyl ketals predominated significantly and were, in some cases, almost the exclusive product. It is argued that this ketal selectivity is in part caused by hydrogen bonding between ethanol and the aryloxy group.