Synthesis of optically active butenolides via chromium alkoxycarbene complexes: total synthesis of (+)-tetrahydrocerulenin and two butenolides from the marine sponge Plakortis lita
摘要:
Optically active butenolides were synthesized from the corresponding cyclobutanones, derived from the photolysis of chromium alkoxycarbene complexes and optically active ene-carbamates. The cyclobutanones were oxidized (Baeyer-Villiger) to the corresponding lactones, and subsequent base-induced elimination of the beta-oxazolidinone ring provided optically active butenolides efficiently. The butenolides were utilized in the syntheses of (+)-tetrahydrocerulenin and two marine natural products.
Synthesis of N-Vinyloxazolidinones and Morpholines from Amino Alcohols and Vinylsulfonium Salts: Analysis of the Outcome's Dependence on the N-Protecting Group by Nanospray Mass Spectrometry
作者:Muhammad Yar、Sven P. Fritz、Paul J. Gates、Eoghan M. McGarrigle、Varinder K. Aggarwal
DOI:10.1002/ejoc.201101272
日期:2012.1
in annulation reactions with diphenylvinylsulfonium triflate has been investigated. Although tosyl and sulfinamide groups give morpholines in high yields, the use of N-Cbz leads to a high-yielding synthesis of N-vinyloxazolidinones. The reactions were monitored by nanospray MS/MS, which revealed why reactions are successful and the fate of reactive intermediates in the unsuccessful reactions.
Synthesis of 4-Alkyl-4-alkoxybutenolides Having Unsaturated Side Chains via Chromium Carbene Complex Photochemistry: (+)-Cerulenin
作者:Tracey E. Kedar、Michael W. Miller、Louis S. Hegedus
DOI:10.1021/jo960664k
日期:1996.1.1
photochemical reaction between optically active ene carbamates and chromium alkoxycarbene complexes containing unsaturated aliphatic side chains was further developed. Although remote olefinic groups, including conjugated dienes, were tolerated, a homoallylic side chain underwent intramolecularreaction to give a strained cyclobutanone. (+)-Cerulenin was synthesized utilizing the photochemical reaction of an
De Novo Synthesis of 4‘-Ethoxy Nucleoside Analogues
作者:Louis S. Hegedus、Lisa Geisler、Andrew G. Riches、Sarri S. Salman、Gisela Umbricht
DOI:10.1021/jo020151f
日期:2002.11.1
Butenolides 5a and 13 were used as opticallyactive templates in the de novo synthesis of 4'-disubstituted nucleoside analogues. The butenolides were reduced and acylated in situ to give acetates 10 and 14. Vorbrüggen coupling gave the protected nucleoside analogues 11 and 15. Reduction of 11 gave 4'-ethoxy-2',3'-dideoxythymidine (6) and deprotection of 15 gave 4'-ethoxy-2',3'-dideoxydidehydrothymidine
Effect of β-Substituents on the Regioselectivity of the Diazomethane Ring Expansion of α-Methyl-α-methoxycyclobutanones to Cyclopentanones
作者:Lisa M. Reeder、Louis S. Hegedus
DOI:10.1021/jo990226o
日期:1999.4.1
The ring expansion of 22 differently beta-substituted alpha-methyl-alpha-methoxycyclobutanones by diazomethane was studied. Migration of the less-substituted alpha-carbon was favored with the single exception of a very sterically hindered beta-benzyloxy beta-substituent.
Synthesis of optically active ene carbamates from chromium carbene complexes: use in palladium(II)-assisted synthesis of relays to (+)-thienamycin
作者:John Montgomery、Gary M. Wieber、Louis S. Hegedus
DOI:10.1021/ja00173a012
日期:1990.8
prepare opticallyactivechromium carbene complexes containing the oxazolidinone moiety led instead to an efficient and general synthesis of opticallyactive ene carbamates. One of these has been subjected to palladium(II)-assisted carboacylation, and complete control of stereochemistry was observed. This compound was converted to a key relay to (+)-thienamycin in good chemical and very high optical yield
尝试制备含有恶唑烷酮部分的光学活性铬卡宾配合物,反而导致了光学活性烯氨基甲酸酯的有效和通用合成。其中之一已进行钯 (II) 辅助的碳酰化,并观察到立体化学的完全控制。该化合物以良好的化学和非常高的光学产率转化为 (+)-硫霉素的关键中继