The synthesis of velloziolide via Nicholas reaction based gamma-carbonyl cations.
The total synthesis of the 9,11-seco-rosane diterpene velloziolide (1) has been accomplished by employing the Nicholas reaction chemistry of 2a as a gamma-carbonyl cation equivalent. An initial model study demonstrated the utility of Nicholas reactions of 2 in the generation of 4-arylalkynoate-Co(2)(CO)(6) complexes, and in conjunction with Gilman cuprate addition and Johnson-Claisen rearrangement chemistry, the preparation of a 3-methyl-3-vinyl-4-arylalkanoate model for velloziolide. The Nicholas reaction/gamma-carbonyl cation methodology was then employed twice in the total synthesis to incorporate onto 3,4-methylenedioxytoluene the 4-carbon unit that became the gem-dimethyltetralin portion of the velloziolide and, subsequently, to incorporate the gamma-arylalkanoate function of the epsilon-lactone.
Green
James R
JR
Department of Chemistry and Biochemistry, University of Windsor, Windsor, ON, N9B 3P4, Canada. jgreen@uwindsor.ca
Tjeng
Andy A
AA
D000480:Alkynes / Q000737:chemistry*; D002412:Cations / Q000737:chemistry; D003035:Cobalt / Q000737:chemistry; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D013237:Stereoisomerism
D000480:Alkynes; D002412:Cations; D004224:Diterpenes; D009942:Organometallic Compounds; C545380:velloziolide; D003035:Cobalt