Taxol verbenone

One method of synthesis of taxol analogues starts with a-pinene (8), the readily available and inexpensive monoterpene derived from the processing of turpentine from the pine tree (200). The a-pinene is oxidized to verbenone, which is then alkylated and converted to taxol analogues in a multistep process. 

Additional examples of selenophene ring-formation reaction that result from the treatment of 1,4-dienes with selenium dioxide have been reported. For example, treatment of verbenone derivative 116 with selenium dioxide in the presence of pyridine gave fused selenophene 117 in 92% yield (Equation 19) <20010L3161, 2002JOC6553>. Additional applications of this reaction include taxol analog 150 <1997BML1941> and a [l]benzopyrano[3,2-/ ]-selenophene-9-one derivative <2001SAA1427>. 

The C-ring of baccatin III was elaborated through the C-3 position, which was used as a base on which to build aldehyde side chain of 14.4.16. Aldol cyclization and protection then gave 14.4.17, which was converted to baccatin III (14.4.23) or 10-deacetylbaccatin III (14.4.22) by the reactions shown. The overall synthesis, at 37 steps from verbenone, is claimed to be the shortest reported synthesis of taxol. 

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See also in sourсe #XX -- [ , , ]

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