An efficient Synthesis of Acetylenic ?- and ?-Hydroxy Ketones, ?- and ?-keto acids, and ?- diketones via addition of 1-alkinyllithium compounds to ?- and ?-lactones
摘要:
2-Hydroxy-6-alkyn-5-ones 3, 1-hydroxy-5-alkyn-4-ones 4, and 1-hydroxy-6-alkyn-5-ones 5 are conveniently obtained in exellent yields through a highly selective monoaddition of an 1-alkynyllithium compound 2 to gamma-valerolactone (1 a), gamma-butyrolactone (1 b) or delta-valerolactone (1 c). They are oxidized by pyridinium dichromate or Jones reagent to the corresponding acetylenic 1,4-diketones 6, 4-oxo carboxylic acids 7, and 5-oxo carboxylic acids 8, respectively.
(HMe2SiCH2)2: A Useful Reagent for B(C6F5)3-Catalyzed Reduction–Lactonization of Keto Acids: Concise Syntheses of (–)-cis-Whisky and (–)-cis-Cognac Lactones
(HMe2SiCH2)2 has been utilized as a useful reagent for B(C6F5)3-catalyzed reduction–lactonization of keto acids to synthesize γ- and δ-lactones. The process led concisely to (–)-cis-whisky and (–)-cis-cognac lactones in respective overall yields of 32% and 36%.
Catalytic Ynone–Amidine Formal [4 + 2]-Cycloaddition for the Regioselective Synthesis of Tricyclic Azepines
作者:T. Prabhakar Reddy、Jagjeet Gujral、Pritam Roy、Dhevalapally B. Ramachary
DOI:10.1021/acs.orglett.0c03711
日期:2020.12.18
A Ca(OTf)2- and self-promoted ynone–amidine atom-economic formal [4 + 2]-cycloaddition of various ynones with amidines is reported for the construction of highly functionalized tricyclic azepines. High reaction rate, ease of operation, and high product selectivity with wide substrate scope are the key advantages of the present annulation protocol.
Regioselective synthesis of oxepinones and azepinones by gold-catalyzed cycloisomerization of functionalyzed cyclopropyl alkynes
作者:Jesús M. Fernández-García、Patricia García-García、Manuel A. Fernández-Rodríguez、Alexandra Pérez-Anes、Enrique Aguilar
DOI:10.1039/c3cc46238b
日期:——
A regioselective synthesis of oxepinones and azepinones in good to excellent yields from alkynylcyclopropanecarboxylic acid derivatives is described. This novel cycloisomerization cascade process consists of a nucleophilic addition followed by a cyclopropane ring-opening, where both donor and acceptor groups are required as substituents of the cyclopropane ring.
4-aminobiphenyl derivative arylamine compounds are formed by providing an iodinated organic compound; substituting the iodinated organic compound at carboxylic acid groups thereof to provide ester protecting groups; conducting an Ullman condensation reaction to convert the product of step (ii) into an arylamine compound; and conducting a Suzuki coupling reaction to add an additional phenyl group to the arylamine compound in the 4-position relative to the nitrogen.
Trichloromethylative olefin lactonization was reported. A photoredox iridium catalyst irradiated with blue LEDs promoted the reaction without using hazardous reagents. The mechanistic studies were performed by experimental and theoretical means. The trichloromethyl moiety of the product could be converted to the corresponding dichloroalkene and chloroalkyne in addition to the carboxyl group.
报道了三氯甲基化烯烃内酯化。用蓝色 LED 照射的光氧化还原铱催化剂在不使用危险试剂的情况下促进了反应。通过实验和理论手段进行了机理研究。除羧基外,产物的三氯甲基部分还可转化为相应的二氯烯烃和氯炔。