Dimeric products from the dissolving metal reduction of camphor

✍ Scribed by John W Huffman; Richard H Wallace; William T Pennington

• Publisher: Elsevier Science
• Year: 1988
• Tongue: French
• Weight: 237 KB
• Volume: 29
• Category: Article
• ISSN: 0040-4039
• DOI: 10.1016/s0040-4039(00)86103-1

✦ Synopsis

Various dissolving metal reductions of (+)-camphor afford one of two pinacols frequently accompanied by a dimeric product in which one bicycloheptane unit has been cleaved.

Similar reductions of (+)-camphor afford various mixtures of (+I-exo-endo, (+I-endo-endo and meso endo-endo pinacols. The structures of two of these products were confirmed by X-ray crystallography.

A number of studies of the mechanism of dissolving metal reduction of ketones to secondary alcohols have been carried out, frequently using camphor as substrate2. In addition to mixtures of alcohols it is known that reduction of (+)-camphor under various conditions affords two diastereomeric pinacols.

3 On the basis of UWR data, Bautenstrauch a$siSned exo-endo structure 1 to the pinacol, mp 113-115', obtained by Li/XH second pinacol was assiSned endo-endo structure 2 2c3 reduction of (+)-camphor.2c'3b The and 157O. obtained by Beckmann 3a x is presumably the same pinacol. mp and later by Huckel & ,1.3b using I?a/Kt20 or Ua/XH3. The relative yields and stereochemistry of these pinacols appear to be very sensitive to the conditions of reduction. 2 Ketyls are implicated in the production of both secondary alcohols and pinacols and an investigation of the factors governing pinacol formation should provide additional insight