Syntheses of Strychnos- and Aspidospermatan-Type Alkaloids. 6. Total Syntheses of (.+-.)-Echitamidine, (.+-.)-Alstogustine, (.+-.)-19-epi-Alstogustine, and (.+-.)-Akuammicine
摘要:
19-Oxodihydroakuammicine was obtained in a three-pot sequence, in 25% overall yield based on a new condensation-sigmatropic rearrangement sequence. Reductions-and quaternization reactions furnished the title compounds.
Syntheses of Strychnan- and Aspidospermatan-Type Alkaloids. 9.<sup>1</sup> The Enantioselective Generation of Tetracyclic ABCE Intermediates by a Tandem Condensation, [3,3]-Sigmatropic Rearrangement, and Cyclization Sequence
作者:Martin E. Kuehne、Feng Xu
DOI:10.1021/jo970207j
日期:1997.11.1
tryptophan-derived benzyl 2-(benzylamino)-3-[3-[2-[(methoxycarbonyl)methyl]indolyl]]propionate gave tetracyclic hexahydro-1H-pyrrolo[2,3-d] intermediates with stereoselective placement of substituents for cyclization to pentacyclic Strychnos alkaloids. The benzyl ester moiety was readily removed by formation of a corresponding nitrile and reduction, thus providing enantioselective syntheses of the tetracyclic
A simple and highly stereoselective route to E-.alpha.,.beta.-unsaturated aldehydes
作者:Moncef Bellassoued、Assieh Majidi
DOI:10.1021/jo00061a027
日期:1993.4
Zinc bromide mediated reaction of alpha,alpha-bis(trimethylsilyl)-tert-butylacetaldimine (3) with a wide range of aldehydes takes place under mild conditions and affords the corresponding alpha,beta-unsaturated aldehydes in good yields and with very high E stereoselectivity (>98%). This procedure is successfully applied to the preparation of intermediates for retinoid and natural product synthesis.
Silylenolether-Funktionalisierung, 3. Mitt. Regioselektive Acylierung von Trimethylsilylenolethern mit 2-Alkoxy-1,3-dioxolanen ? Synthese von ?- und ?-gesch�tzten Dicarbonylverbindungen