Ascaridole synthesis

This review is concerned with the synthesis, spectroscopic characterisation, and reactions of saturated bicyclic peroxides. Four years ago such compounds were virtually unknown, yet the first example 2a had been prepared as early as 1938 by catalytic hydrogenation of the naturally occurring peroxide ascaridole 1 (Eq. 1) l). 

Singlet oxygen adds to cyclic 1,3-dienes to afford 1,4-endoperoxides 609). This type of reaction has first been applied successfully to the synthesis of ascaridole from a-terpinene 610) (6.4) and of the vesicatory compound cantharidine 6U) (6.5) some 25 years ago. 

Conjugated cycloalkadienes4l3 17 are converted to bicyclic endoperoxides that may undergo thermal or photochemical rearrangement to yield diepoxides.374-377 1,3-Cyclopentadiene and 1,3-cyclohexadiene give endoperoxides exclusively. The first synthesis of the naturally occurring ascaridol (52) was also carried out in this way 418,419... 

Ascaridole, l-Methyl-4-i I-methylethyli-2 3-di-oxa bicycl o[2.2.2]oct-5-ene 1,4-peroxido -p-men thene -2 Ascarisin. C10H]4O2 mol wt 168.23. C 71.39%, H 9.59%, O 19.02%. An organic peroxide which constitutes 60-80% of oil of chenopodium. Synthesis from or-terpinene by treatment with oxygen, chlorophyll, and light Schenck, Ziegler, Naturwiss- 1964, 157. Purification Beckett et al, J. Pharm. Pharmacol 7, 55 (1955). 

An early example of a multi-phase microreaction was reported by Wootton et al., who demonstrated the continuous photochemical production of singlet oxygen and its use in organic synthesis for the cydooxidation of a-terpinene to ascaridol (Scheme 16.5) [10]. 

Arylhydrazines, reaction with MA, 85, 86 Arylhydrazones, reaction with MA, 83 Arylthiosuccinic anhydrides, melting points, 50 Ascaridol, 466 Aspartic acid, 47, 48 synthesis from fumaric acid, 47 Aspartic acid derivatives, preparation with oxizime-MA reaction, 228... 

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