ChemInform Abstract: Total Synthesis of (.+-.)-Veadeiroic Acid (original) (raw)

Minor cleisthantane and tetranorfriedolabdane from Vellozia flavicans

Phytochemistry, 1995

Six diterpenes with the cleistanthane skeleton have been identified from Velloziaflavicans, three of which; 8,11,13-cleistanthatrien-7-one-17-oic acid, 8,11,13-cleistanthatrien-7-one-19-oic acid and 8,11,13-cleistanthatrien-17,19-dioic acid are reported herein for the first time as natural products. Two tetranorditerpenes with a friedolabdane skeleton have also been isolated from this same plant.

Diterpenoids from Vellozia flavicans

Phytochemistry, 1987

EXPERIMENTAL The air dried aerial parts of M. zeylanica (400 g, collected in Sri Lanka, voucher No. NKBA 34) was extracted with Et&MeOH-petrol, 1: 1: 1, and worked-up as reported previously [9]. By CC (SiOl) and TLC (SiOz, PF 254) 40 mg /?farnesenc, 20 mg squakne, 25 mg dammadienyl acetate, 20 mg caryophyllen-1,10_epoxidt, 20 mg 1 and 5 mg S$dihydroxy-6,7,8,~-tetmmethoxyflavone were obtained and identified by ~rn~r~ng the400 MHz 'H NMR spectra with those ofauthentic material. The polar CC fraction (Et+MeOH, 9: 1) gave by HPLC (RP 8, MeOH-HsO, 7:3, ca 100 bar) 2 mg 3 (R, 3.5 min) and 10 mg 2 (R, 4.0 min). IO, 11 -Dihydromicroglossic acid (2). Colourlcss oil; IR v$'$cm -I: 35OO-2700,172O (COIH), 1740 (C02R); MS m/z (rel. int.): 364.225. [Ml+ (2) (cak. for CIIHsIO,: 364.225). 346 [M-i&O]-(14),332[M-MeOH-J'(5).324[346-MeOH]' (7). 108 (51). 95 (74). 94 (72), 83 (98), 82 (98), 81 (68), 69 (100). Microg/ossic aeid (3). Colourless oil; MS m/r (rel. int.): 362.209 [M] + (6) (cak. for CIt HJ005: 362.209). 330 [M -MeOH] ' (5). 284 [330-HCOzH]+ (IO), 256 [284-CO]' (12), 121 (60). 69 (100).

Clerodanes and tetranorclerodane from Vellozia bicolor

Phytochemistry, 1994

new substances isolated from the ethyl acetate extract of roots, stem and leaf sheaths of J'eZlozin bicolor were characterized as 2-oxo-5r,8a-cleroda-3,13-dien-l6,15_olide and the tetranorclerodane diterpene 2-oxo-5a,8a-13,14,15,16-tetranorclerod-3-en-12-oic acid. In addition, the clerodane diterpene 15,16-epoxy-2-oxo-5a$a-cleroda-3,13(16),14-triene, previously obtained by chemical transformation, was obtained.

Formal total synthesis of an A-seco mevinic acid

Tetrahedron, 1997

Cmhined use oJchemcn1 und enzymatic merhodsfor a short access to the JullyJunctionali:ed B-ring. the 2: I'. &I, 4u-ietmsub.Ftituted cyclohexene unit, ofA-seco mevinic acids is presented.