نتایج جستجو برای: αβ unsaturated compounds
تعداد نتایج: 242522 فیلتر نتایج به سال:
Vinylcyclopropane and bicyclopropyl C6 compounds are studied as diene precursors in the Diels-Alder reaction. Their rearrangement under different thermal and microwave conditions leads to specific isomeric hexa-, pentaor butadienes, condensed with maleic anhydride as a dienophile. Adduct stereochemistries were compared to those of previously-synthesized model compounds, and are fully characteri...
A new series of carbapenems, having a saturated or partially unsaturated heterocycle at C-2, has been synthesised. The in vitro antibacterial activity of these compounds and their stability to human dehydropeptidase-1 (DHP-1) are described. The stereochemistry of the C-2 side-chain and the presence of a double bond in the heterocycle were shown to have significant effects on the stabilities of ...
One pot syntheses of furan, thiophene, and pyrrole were accomplished by oxidative deacetylation using Mn(III)/Co(II) catalysts and the Paal-Knorr reaction from 1,5-dicarbonyl compounds, which are prepared from the conjugate addition of ethyl acetoacetate to α,β-unsaturated carbonyl compounds. The oxidative deacetylation and reductive cyclization of β-ketoesters derived from ethyl acetoacetate a...
Porphyrins with (un)saturated side–chains containing boron residues were developed as synthons for porphyrin functionalization. Porphyrins with mono and bis-substituted unsaturated boronyl residues were prepared in good yields (52–66 %) using a cross–metathesis approach in the presence of Grubbs I-generation catalysts. In all cases complete E–stereoselectivity (100 %) was observed. Furthermore,...
The scope, generality, and mechanism of the Dess-Martin periodinane-mediated cyclization reaction of unsaturated anilides discovered during the total synthesis of the CP-molecules (phomoidrides A and B) are delineated. A plethora of heterocyclic compounds are accessible by employing gamma,delta-unsaturated amides (derived from anilines and carboxylic acids), urethanes, or ureas (derived from is...
A new flexible approach for the stereoselective synthesis of substituted 1H-pyrrol-2(5H)-ones and 3,6-dihydro-1H-pyridin-2-ones has been developed. The general strategy employed the stereoselective reduction of a series of α,β-unsaturated ketones under chelation control to give the corresponding allylic alcohols. Overman rearrangement to install the key C-N bond followed by conversion to either...
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