Nitrile Oxides, Nitrones, and Nitronates in Organic Synthesis : Novel ...

APPLICATIONS OF NITRILE OXIDES 91
The synthesis of new 11-deoxyprostaglandin analogs with a cyclopentane
fragment in the ω-chain, prostanoid 418, has been accomplished by a reaction
sequence involving nitrile oxide generation from the nitromethyl derivative
of 2-(ω-carbomethoxyhexyl)-2-cyclopenten-1-one, its 1,3-cycloaddition to
cyclopenten-1-one and reductive transformations of these cycloadducts (459).
Diastereoisomers of a new prostanoid precursor 419 with a 4,5,6,6a-tetrahydro-
3aH -cyclopent[d]isoxazole fragment in the ω-chain have been synthesized.
Reduction of 419 gives novel 11-deoxyprostanoids with modiÞed α-andω-chains
(460).
HO
O
CO 2Me
O (CH2)6CO2Me
O
N
O
O
418 419
The 1,3-dipolar addition to terminal alkenes of nitrile oxides, generated from
nitromethylene derivatives of bicycloheptane, provides 9,11-ethano-13,15isoxazolinoprostanoids,
PGH analogs, with alkyl, phenyl, or additional
heterocyclic fragment in the ω-chain (461). Chemical transformations of 9,11ethano-13,15-isoxazolinoprostanoids
furnish prostanoids with bifunctional fragments
of β-hydroxyketone and α-aminoalcohol in the ω-chain. The reaction of
β-hydroxyketones with methanesulfonyl chloride gives rise to prostanoids with
an enone component in the ω-chain. 9,11-Ethano-16-thiaprostanoids have been
prepared, for the Þrst time, by nucleophilic addition of thiols to the polarized double
bond in the ω-chain. The 1,3-dipolar addition to terminal alkenes of nitrile
oxides, generated from nitromethylene derivatives of bicycloheptane provides
9,11-ethano-13,15-isoxazolinoprostanoids with an alkyl, phenyl, or additional
heterocyclic fragment in the ω-chain (462).
A total synthesis of the sesquiterpene ( ± )-illudin C 420 has been described.
The tricyclic ring system of the natural product is readily quickly assembled
from cyclopropane and cyclopentene precursors via a novel oxime dianion coupling
reaction and a subsequent intramolecular nitrile oxide—oleÞn cycloaddition
(463).
H 2C
Me
O
OH
420
Me
Me