Constituents of the acidic part of commercial Brazilian lantana oil

The acidic part of Brazilian lantana oil contains mainly new bisabolene and tricyclic helifolene derivatives. 3-Formyl-helifolen-12-oic acids 14, 16, 11-formyl-helifolen-15-oic acids 10, 12, 6,10-epoxybisabol-2- 18, 20, 22, 2 4, and -3-en-12-oic acids 19, 21, 23, 25, gamma-(26) and ar-curcumen-15-oic acids (27), as well as the known ar-curcumen-12-oic acid (28) and amorpha- 4,9,11-trien-12-oic acid, were characterized as their methyl esters. The bi functionalized methyl helifolenoates 10, 12, 14, 16 were reduced with NaBH4 to the corresponding hydroxy esters 11, 13, 15, 17. Their configuration wa s clarified by NOED spectra. The helifolen-12- (1a-4a) and -15-oic acids (5 a) are present in the acidic part only as traces. Their spectral data were obtained by isolation from an autoxidized fraction of the known aldehydes.( 1) The parent helifolane (syn. khusiane or allo-cedrane) skeleton 8/9 was p repared by stepwise reduction of esters 1b-4b with LiAlH4 and H-2/Pd/C to y ield the helifolanols 6 and 7. Treatment of 6, 7 with O-p-tolylchlorothiono formate gave the corresponding thionocarbonates which were reduced with tri s(trimethylsilyl)silane to afford helifolanes 8 and 9. Copyright (C) 2001 J ohn Wiley & Sons, Ltd.