Improved Synthesis of the -Glucuronide/Glycoside of 4-Hydroxybenzylretinone (4-HBR).

Improvements in the synthesis of carbon-linked glucuronide/glucoside conjugates of cancer chemopreventive retinoids have been achieved starting with 2,3,4,6-tetra--benzyl-D-glucopyranose. The revised approach demonstrates better yields, eliminates the use of an expensive, carcinogenic protecting group reagent, and avoids much painstaking chromatography. The new approach should allow synthesis of larger quantities of the agents for detailed animal and mechanistic studies.

Efficient, Low-Cost Synthesis of Retinal (Vitamin A Aldehyde).

Inexpensive retinyl acetate has been subjected to transesterification followed by allylic oxidation to give retinal in 98% yield as a 92:8 mixture of all-trans/13-cis isomers after chromatographic separation. More convenient methods of isolating the all-trans isomer have also been employed.