Stereoselective reduction of .gamma.-oxobutanoic acids using DIBAL-H and zinc chloride
摘要:
A variety of gamma-aromatic gamma-ketobutanoic acids can be reduced selectively, under optimized conditions, by the use of DIBAL-H and ZnCl2 to provide the (RS,SR)-gamma-aryl-gamma-hydroxy-beta-methylbutanoic acids. Further evidence has been gathered to support the hypothesis that the reaction proceeds by formation of a seven-membered ring complex with the aluminium or zinc atom bridging the ketone and carboxyl groups which preceeds the reduction step and that this templated reduction accounts for observed high diastereoselectivity. Also we have shown that some gamma-aryl-gamma-butyrolactones can be easily transformed via an oxidative cleavage of the aromatic ring to provide selective synthesis of either cis- or trans-tetrahydro-3-methyl-5-oxo-2-furancarboxylic acid derivatives.
furans has been developed. The operationally simple one‐pot method is initiated by singlet oxygen, but also later uses ground state oxygen (triplet oxygen) and is dependent on methylene blue which acts in a dual role; first as a sensitizer and then as a radical initiator in the dark.
Addition/Oxidative Rearrangement of 3-Furfurals and 3-Furyl Imines: New Approaches to Substituted Furans and Pyrroles
作者:Ann Rowley Kelly、Michael H. Kerrigan、Patrick J. Walsh
DOI:10.1021/ja710988q
日期:2008.3.1
oxidative rearrangement proceeds through an unsaturated 1,4-dialdehyde intermediate. The alcohol then cyclizes onto an aldehyde, resulting in the elimination of water and rearomatization. On the basis of this proposed mechanism, we found that 3-furyl imines undergo the addition of organometallic reagents to provide furyl sulfonamides. Under the oxidative rearrangement conditions, 2-substituted 3-formyl
Oxidation of 3-Furfurylcarbinols with Bromine in Acetone-Water
作者:Piin-Jye Harn、Chu-Chung Lin、Hsien-Jen Wu
DOI:10.1002/jccs.200800035
日期:2008.2
Oxidation of 3-furfurylcarbinols 3a-e and 7 with bromine in acetone-water solution gave the 2-substituted-3-furfurals 4a-e and 8 in good yields, respectively. Reaction of 2-alkyl-3-furfurylcarbinols 9a and 9b with bromine in acetone-water gave the bromoalkyl 3-furfuryl ketones 10a and 10b as the major products. A reaction mechanism via the cis-trans isomerization of the 2-ene-1,4-diones 13 and 14 was
An Exploratory Study of Type II [3 + 4] Cycloadditions between Vinylcarbenoids and Dienes
作者:Huw M. L. Davies、Rebecca L. Calvo、Robert J. Townsend、Pingda Ren、R. Melvyn Churchill
DOI:10.1021/jo991959b
日期:2000.7.1
dirhodium tetracarboxylate catalyzed decomposition of vinyldiazoacetates. The [3 + 4] cycloaddition is generally considered to occur by a tandem cyclopropanation/Cope rearrangement, although evidence is presented that with these substrates the [3 + 4] cycloaddition may occur in a concerted manner.