Kessanol Knoevenagel reaction

In connection with a synthesis of the hydroazulenic sesquiterpene kessanol (304), Knoevenagel condensation of photocitral-A (302) with ethyl cyanoacetate was found to give (303) as a single isomer. The following sequence includes an intramolecular Prins reaction initiated with SnCU. In Isobe s synthesis of vemolepin (307) the two carbons of the -y-iactone are introduced by a Knoevenagei condensation. Reaction of ketone (305) with di-f-butyl maionate followed by treatment with DBU affords (306), which is transformed to the a,a -dihydroxy compound (308). Hydrolysis of the esters foliowed by decarboxy-iation, formation of the y-lactone, Mannich reaction and elimination yields vemolepin (307 Scheme 58).3"... 

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See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ , ]

See also in sourсe #XX -- [ ]

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