Microwave- and Photoirradiation-Induced Staudinger Reactions of Cyclic Imines and Ketenes Generated from α-Diazoketones. A Further Investigation into the Stereochemical Process
作者:Yong Liang、Lei Jiao、Shiwei Zhang、Jiaxi Xu
DOI:10.1021/jo048328o
日期:2005.1.1
with a series of acyclic and cyclicimines were investigated under both microwave and photoirradiation conditions. The results indicate that the zwitterionic azabutadiene-type intermediates yielded from imines and ketenes undergo a conrotatory ring closure exclusively to produce β-lactams. It is notable that no Woodward−Hoffmann product was found under the ultraviolet irradiation. The photoirradiation-induced
ketenes in the Staudingerreaction. On the basis of the reactions of S-phenyl diazothioacetate with imines under the catalysis of Rh 2 (OAc) 4 a method for the synthesis of 3-phenylthio β-lactam derivatives has been developed previously. In this paper, a more convenient and improved procedure was achieved, which simplified the synthesis of S-phenyl diazothioacetate and made the reaction work well without
Thionation ofN-(?-Halogenoalkyl)-Substituted Amides withLawesson's Reagent: Facile Synthesis of 4,5-Dihydro-1,3-thiazoles and 5,6-Dihydro-4H-1,3-thiazines
作者:Yasuhiro Kodama、Mayuko Ori、Takehiko Nishio
DOI:10.1002/hlca.200590000
日期:2005.2
The thionation and cyclization of N-(ω-halogenoalkyl)-substitutedamides (and related compounds) with Lawesson's reagent (LR=2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide) has been investigated. Treatment of the amides 1 with LR gave the corresponding thioamides 2 in moderate to good yields (Table). The latter, upon treatment with base, afforded, either in a separate step or in