Dianion of Sulfinylacetone as a Synthetic Equivalent of .BETA.-Enolate of Propionic Acid: A Novel Synthesis of Carboxylic Acids from Alkyl Halides with Three-Carbon Elongation
作者:Tsuyoshi Satoh、Kentaro Imai
DOI:10.1248/cpb.51.602
日期:——
dianion of phenylsulfinylacetone with alkylhalides afforded beta-keto sulfoxides, which were first chlorinated with hexachloroethane and then treated successively with KH and t-BuLi to give carboxylic acids in three-steps in moderate overall yields from the alkylhalides. This procedure affords a good method for a synthesis of carboxylic acids fromalkylhalides with three-carbon elongation.
Suppression of β-Hydride Elimination in the Intramolecular Hydrocarboxylation of Alkynes leading to the Formation of Lactones
作者:Zhibao Huo、Nitin T. Patil、Tienan Jin、Nirmal K. Pahadi、Yoshinori Yamamoto
DOI:10.1002/adsc.200600507
日期:2007.3.5
Palladium-catalyzed intramolecular cyclization of the alkynoic acids was studied which gave the five- and six-membered lactones in moderate yields. The reaction can be conducted simply by heating a toluene solution of alkynoic acids at 100 °C in the presence of catalytic amounts of Pd(PPh3)4 and (o-tol)3P. The key for this transformation is the use of phosphines, instead of carboxylic acids, as an
Intramolecular aminopalladation of alkynylamines gave intermediary alkenylpalladium compounds that hydrolyzed and isomerized to thermodynamically stable cyclic imines. Treatment of 3-alkynylamines with a catalytic amount of PdCl2(MeCN)2 gave exclusively 1-pyrrolines in good yields; 5-alkynylamines afforded 2,3,4,5-tetrahydropyridines selectively. Treatment of 4-alkynylamines with Pd(II) afforded mixtures of both 5- and 6-membered cyclic imines. Applications to the synthesis of some naturally occurring alkaloids are also described.
164. Syntheses of long-chain acids. Part VI. Acetylenic acids and cis,cis-docosa-5,13-dienoic acid
作者:D. E. Ames、A. N. Covell、T. G. Goodburn
DOI:10.1039/jr9650000894
日期:——
New functions of (arene)tricarbonylchromium(0) complexes as hydrogenation catalysts: stereospecific semihydrogenation of alkynes and highly chemoselective hydrogenation of .alpha.,.beta.-unsaturated carbonyl compounds