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Application of Electrocyclic Ring-opening and Desymmetrizing Nucleophilic Trappings of meso-6,6-Dibromobicyclo3.1.0hexanes to Total Syntheses of Crinine and Haemanthamine Alkaloids.

07:00 EST 6th February 2019 | BioPortfolio

Summary of "Application of Electrocyclic Ring-opening and Desymmetrizing Nucleophilic Trappings of meso-6,6-Dibromobicyclo3.1.0hexanes to Total Syntheses of Crinine and Haemanthamine Alkaloids."

The thermally-induced electrocyclic ring-opening of C2-symmetric (meso) 6,6-dibromobicyclo[3.1.0]hexanes such as 10 in the presence of the chiral, non-racemic 1°-amine 28 afforded a ca. 1:1 mixture of the diastereoisomeric and chromatographically separable 1-amino-2-bromo-2-cyclohexenes 37 (42%) and 38 (45%). Each of these was elaborated, over thirteen steps including Suzuki-Miyaura cross-coupling, radical cyclization and Pictet-Spengler reactions, into (-)- or (+)-crinane (1 or ent-1, respectively). Variations on these protocols have been applied to the total syntheses of (+)- and (-)-11-hydroxyvattitine [(+)- and (-)-3], (+)- and (-)-bulbispermine [(+)- and (-)-4], (+)- and (-)-haemanthidine [(+)- and (-)-5], (+)- and (-)-pretazettine [(+)- and (-)-6] and (+)- and (-)-tazettine [(+)- and (-)-7] as well as (±)-hamayne [(±)-8] and (±)-apohaemanthamine [(±)-9]. A number of these alkaloids have been synthesized for the first time.

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This article was published in the following journal.

Name: The Journal of organic chemistry
ISSN: 1520-6904
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