Takeda et al. reported the formation of medium-sized carbo- and oxacycles by
using a Brook rearrangement-mediated [3+4]-annulation reaction [138]. This method
was then employed in a formal synthesis of (+)-laurallene [139] and (Æ)-prelaureatin
[140]. As shown in Scheme 36, for the preparation of (+)-laurallene, acryloyl silane
174 and the unsaturated seven-membered ketone 175 were converted, using Davis’
oxaziridine, to 176 by a one-pot [3+4]-annulation/oxidation sequence. Bicyclic
intermediate 176 was then submitted to an oxidative cleavage producing the eightmembered ether 177, which was further transformed to 178, an intermediate in the
Crimmins’ synthesis of (+)-laurallene.
Scheme 34 Strategy of intramolecular amide enolate alkylation developed by Kim et al.
Scheme 35 Application of the Kim et al. method to the total synthesis of (E)-cladiellin
Scheme 36 One-pot [3+4]-annulation/oxidation reaction reported by Takeda et al.
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E. Soriano and J. Marco-Contelles
using a Brook rearrangement-mediated [3+4]-annulation reaction [138]. This method
was then employed in a formal synthesis of (+)-laurallene [139] and (Æ)-prelaureatin
[140]. As shown in Scheme 36, for the preparation of (+)-laurallene, acryloyl silane
174 and the unsaturated seven-membered ketone 175 were converted, using Davis’
oxaziridine, to 176 by a one-pot [3+4]-annulation/oxidation sequence. Bicyclic
intermediate 176 was then submitted to an oxidative cleavage producing the eightmembered ether 177, which was further transformed to 178, an intermediate in the
Crimmins’ synthesis of (+)-laurallene.
Scheme 34 Strategy of intramolecular amide enolate alkylation developed by Kim et al.
Scheme 35 Application of the Kim et al. method to the total synthesis of (E)-cladiellin
Scheme 36 One-pot [3+4]-annulation/oxidation reaction reported by Takeda et al.
348
E. Soriano and J. Marco-Contelles