280 research outputs found
Cobalt(II)Chloride-Catalyzed Chemioselective Sodium Borohydride Reduction of Azides in Water
No full textNaOH-Catalyzed Thiolysis of alpha,beta-Epoxyketones in Water. A Key Step in the Synthesis of Target Molecules Starting from alpha,beta-Unsaturated Ketones
No full textNaOH (0.02-0.3 molar equiv) is an efficient catalyst for the thiolysis reactions of alpha,beta-epoxy ketones with alkyl and aryl thiols in water. Thiolysis of 3,4-epoxyheptan-2-one (1) with thiols 2a-d has been accomplished in mild conditions (30 °C and pH 6 or 9) with complete C-R-regioselectivity and anti-stereoselectivity, and the corresponding anti-beta-carbonyl-beta-hydroxysulfides 3a-d have been prepared in excellent yields (95-98%). Compounds 3a-d, depending on their nature and pH conditions, have undergone dehydration, C-3 epimerization reaction, and retroaldol condensation.
Dehydration of anti-3a-d has been chemoselectively carried out by in situ acidic treatment at
70 °C, giving stereoselectively the related (Z)-vinyl sulfides 4 in 89-94% overall yields. Under NaOHcatalyzed thiolysis conditions, cyclic alpha,beta-epoxyketones 6-9 have shown C-R attack only and spontaneously dehydrated to furnish the corresponding vinyl sulfides in high yields (90-96%). The reactions of calchone oxide (10) with thiols 2b-d have exclusively resulted in the formation of â-carbonylsulfides 10b-d (82-93% yield), coming from the nucleophilic attack at the R-position and retroaldol condensation. To highlight the synthetic utility of this procedure, one-pot multisteps preparation of vinyl sulfides 7b and 7c, vinyl sulfoxides 12 and 13, and 1,5,6,7-tetrahydro-4H-1,2,3-benzotriazol-4-one (14) starting from 2-cyclohexen-1-one (11) have also been reported
Oxirane Ring-Opening Approach Towards the One-Pot Synthesis of (+)-Phenylnorstatine and (-)-Allophenylnorstatine. Award of the first Europa medal -
No full textEnvironmentally Friendly Synthesis of Norstatines in Water
No full text"This book, the first volume in the new Proven Green Syntheses series, presents new reaction pathways and organic and inorganic catalysts involving and including fundamental chemistry. A unique feature of this new series, not found elsewhere, is to include green metrics as a key component of submissions of original works in order to substantiate the level of "greenness" of new chemical processes. It helps fill an expressed need and desire by both academia and industry to incorporate metrics analysis as a means to rigorously define efficiency and sustainability of chemical synthesis. "-
One-Pot Synthesis of 3-Carboxycoumarins via Consecutive Knoevenogel-Pinner Reactions in Water
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Enantioselettive synthesis of b-hydroxy acids via chiral enolates of carboxylic acids and esters
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