Pii: S0040-4020(97)10223-x
نویسندگان
چکیده
The nickel-catalyzed intramolecular cycloaddition of dienes with unactivatable alkynes is found to proceed under mild conditions while the corresponding Diels-Alder cycloaddition of the same substrates either fails or occurs only under forcing conditions. The nickel-catalyzed cycloaddition is also shown to occur with retention of stereochemistry and is not significantly influenced by electronic effects. Finally, the catalyzed process is shown to be applicable to the synthesis of angularly substituted bicycles, including the CD ring systems of steroids and vitamin D. © 1998 Published by Elsevier Science Ltd. All rights reserved.
منابع مشابه
Pii: S0040-4020(97)00801-6
The synthesis of two classes of Philanthotoxin-343 analogs is described. Quantitative information on the antagonism of quisqualate-sensitive ionotropic glutamate receptors of insect muscle by these compounds is presented. © 1997 Elsevier Science Ltd.
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Absfracf: A facile synthesis of four of the eight configurational isomers of phytosphingosine has been performed by employing Wittig and Julia olefination followed by Sharpless dihydroxylation. The set of these four stereoisomers served as model compounds for developing general chemical/CD/NMR protocols for assigning relative and absolute configurations of all phytosphingosine isomers. The proc...
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The diazo group of a series of a-diazo carbonyl compounds can be reduced to the corresponding CH2 group by Bu3SnH under Cu(acac)2-catalytic or photochemical conditions. The mechanistic aspects of this reaction were investigated in some detail, and a possible reaction pathway was discussed. q 2000 Elsevier Science Ltd. All rights reserved.
متن کاملPii: S0040-4020(00)00693-1
ÐKnoevenagel condensation between 3-nitro-2-pyridinecarbaldehyde and diethyl malonate catalyzed by titanium(IV) chloride gave diethyl 3-nitro-2-pyridylidenemalonate which was oxidized with peracetic acid to give corresponding 1-oxide. Reaction of the latter with diethylamine in the presence of primary and secondary alcohols resulted in the reduction of the nitro group and the oxidation of the v...
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