Enantiospecific total synthesis of (-)-4-thiocyanatoneopupukeanane.
Enantiospecific synthesis of the natural enantiomer of the marine sesquiterpene (-)-4-thiocyanatoneopupukeanane (6) is described. The bicyclo[2.2.2]octanecarboxylate 14, obtained from (R)-carvone via Michael-Michael reaction, was transformed into neopupukeananedione 12 by employing rhodium acetate catalyzed intramolecular C-H insertion of the diazo ketones 16 or 19 as the key reaction. Regioselective deoxygenation of the C-2 ketone transformed the dione 12 into neopupukean-4-one 10. Alternately, the keto ester 18 was also transformed into neopupukean-4-one 10 via regioselective deoxygenation of the ketone in 18 followed by intramolecular rhodium carbenoid C-H insertion of the diazo ketone 31. Finally, neopupukean-4-one 10 was transformed into (-)-4-thiocyanatoneopupukeanane 6 via the alcohol 32 and the mesylate 33.
Srikrishna
A
A
Department of Organic Chemistry, Indian Institute of Science, Bangalore 560 012, India. ask@orgchem.iisc.ernet.in
Gharpure
S J
SJ
D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D009570:Nitriles / Q000138:chemical synthesis* / Q000737:chemistry; D012717:Sesquiterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D013057:Spectrum Analysis; D013237:Stereoisomerism
C431207:4-thiocyanatoneopupukeanane; D001643:Bridged Bicyclo Compounds; D009570:Nitriles; D012717:Sesquiterpenes