Tandem cyclisations involving alpha-ketenyl alkyl radicals. New syntheses of the natural triquinanes pentalenene and modhephene.
New synthetic approaches to the angular and propellane sesquiterpene triquinanes (+/-)-pentalenene 2 and (+/-)-modhephene 3, respectively, are described. The syntheses are based on tandem cyclisations involving alpha-ketene alkyl radical intermediates produced from alpha,beta-unsaturated acyl radical species, as highlighted in Schemes 2 and 4.
De Boeck
Benoît
B
School of Chemistry, The University of Nottingham, Nottingham, NG7 2RD, UK.
Harrington-Frost
Nicole M
NM
Pattenden
Gerald
G
D001952:Bridged-Ring Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D003500:Cyclization; D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry; D005030:Ethylenes / Q000737:chemistry; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D007659:Ketones / Q000737:chemistry; D008968:Molecular Conformation; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D013237:Stereoisomerism
D001952:Bridged-Ring Compounds; D003517:Cyclopentanes; D005030:Ethylenes; D005609:Free Radicals; D007659:Ketones; D000081223:Polycyclic Sesquiterpenes; D012717:Sesquiterpenes; C511836:modhephene; C024646:pentalenene; C008223:ketene