Camphor, deuteriation

The synthesis of camphor (80% optical purity) by heating optically pure di-hydrocarvone at 400 °C for 20 h is reminiscent of Money s racemic camphor synthesis (Vol. 1, p. 39) in that both correspond to a biogenetic-type synthesis via enol formation. Further synthetic work on deuteriated camphors (see references therein and Vol. 3, p. 67 Vol. 4, p. 48 Vol. 7, p. 38 for earlier work) includes syntheses of optically pure [8- Hi]-, [8- H2]-, and [8- H3]-(—)-camphor (204) by modification of known reactions (Scheme 5) and the use of an improved Zn-Cu... 

The high-temperature (185—250 °C) base-promoted (Bu OK-Bu OH) P-epimeriza-tion and y-hydrogen abstraction via homoenolate anions) pathway for the inter-conversion of camphor, exo-isocamphanone, and endo-isocamphanone has been traced with the aid of deuterium labelling studies and by the use of deuteriated solvents. ... 

In an interesting paper it is revealed that di-t-butylnitroxide (DTBN) radical induces upheld contact shifts for the X-H proton donor molecules and conforma-tionally dependent downfield shifts for C—H protons in accordance with the W-rule. Methyl protons in close spatial contact with the N-H or O-H proton donor groups exhibit marked DTBN-induced downfield pseudo-contact shifts. The origin of these effects and their potential uses are discussed. Proton shifts for various monoterpenes e.g. camphor, camphor quinone, and pinocarvone) in hexafiuorobenzene are compared with the shifts obtained in other, more conventional, solvents. Unusually large couplings between the OH and adjacent CH protons have been observed for extremely pure samples of syn- and anrt-7-hydroxynorbomene in particular solvents. " The simplification in the spectra of these compounds, of 7-hydroxynor-bornadiene, and of the catalytically deuteriated (exo-addition) derivatives, with the aid of Eu(dpm)3 and Eu(fod)3 is reported in a companion communication. ... 

Synthetic Aspects.— The extraction of reaction mixtures with aqueous sodium hydrogen sulphite has been advocated as a mild procedure for the efficient removal of norbornenone and norbornenol impurities.Deuteriated olefins can be efficiently synthesized from the corresponding arenesulphonylhydrazones. The reaction of R R CHC(R ) NNHS02Ar with an alkyl-lithium in tetramethylethylenediamine produces R R C (CR which, upon quenching with water (or D 2 O), is converted into olefin R R C=CHR (or R R C=CDR ). Treatment of the sulphonylhydrazone derived from camphor by this method gave (442) in quantitative yield with a 95 % [ H2] analysis. ... 

S-oxide reacted with dichlorocarbene under neutral conditions, yielding 9-(dichloromethylene)fiuorene. A convenient method for the preparation of 9- and 10-deuteriated camphors has been introduced in the reduction of the corresponding chlorosulphoxides, for example (191), by deuteriated amalgamated aluminium and/or Raney nickel. ... 

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