New, General, and Practical Preparation of Methyl Ketones via the Direct Coupling of Amides with CH2Cl2 Promoted by TiCl4/Mg
摘要:
The direct coupling of a variety of amides with CH2Cl2 or CD2Cl2 promoted by TiCl4/Mg/THF provides an extremely simple, practical, selective, and efficient approach for the construction of methyl ketones. The efficiency and practicability of this chemistry is illustrated by the very simple synthesis of deuterated methyl ketones.
Transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones catalysed by natural kaolinitic clay
作者:G. K. Jnaneshwara、N. B. Barhate、A. Sudalai、V. H. Deshpande、R. D. Wakharkar、A. S. Gajare、M. S. Shingare、R. Sukumar
DOI:10.1039/a706475f
日期:——
Natural kaolinitic clay efficiently catalyses the transdithioacetalization of acetals, ketals, oximes, enamines and tosylhydrazones with ethane-1,2-dithiol and propane-1,3-dithiol to produce the corresponding dithiolanes in high yields.
Dysoline, a novel chromone alkaloid isolated from Dysoxylum binectariferum, was reported to have selective cytotoxicity for HT1080 fibrosarcoma cells (IC50 of 0.21 μM). Given the scarcity of natural material, a concise synthesis of (+)-dysoline was developed, allowing for further biological evaluation. An enantioselective nucleophile-catalyzed aldol lactonization formed the piperidine ring with control
Reactivite des derives de cyclopropylidene-3 propyle-I
作者:M. Bertrand、G. Leandri、A. Meou
DOI:10.1016/s0040-4020(01)98934-3
日期:1981.1
β-cyclopropylidenic alcohols has been synthesized through the following sequence: (i) Wittig condensation between cyclopropylidenetriphenylphosphorane with appropriate monoprotected 1,3-dicarbonyl compounds; (ii) smooth hydrolysis of acetals (after a necessary transacetalization step) and ketals thus formed; (iii) LAH reduction of aldehydes and ketones (yielding primary and secondary alcohols respectively)
The reaction of substituted 2-alkynyl carbonates with terminal acetylenes in the presence of palladium-phosphine complex and copper iodide as catalysts proceeds in THF to give 1,2-dien-4-ynes (allenyl acetylenes) in good yields. The reaction proceeds by the formation of allenylpalladium complex as an intermediate.
Treatment of propargylic ethers with sodium dispersion in the presence of lithium iodide results in the generation of the corresponding carbanion species via cleavage of the propargylic C–O bond. The anionic species react with trimethoxyborane to yield the allenylboronates including highly substituted ones that are difficult to synthesize.