Full text of DOI:10.1016/S0040-4020(01)93657-9

3171
rearrangements and cyclizations of diterpenoid
was chromatographed on silica gel (50 g): 20% benzene in petroleum ether eluted
12”
Mixture B was separated by prep. VPC on column C at 186” to give
211 mg) (c = 0.62).
In addition
35 mg)
m.p.
25 mg) and
(20;
(19; 112
(P)’ = 272, were isolated.
(100 mg) was dissolved in pyridine (3 drops),
rimuene (22;
(c =
acetate.
(5 drops) added
and maintained at 100” for 28 hr Standing over
and
m.p. 85-86”).
mg) was dissolved in
and HCOOH (270 mg of 97% soln). The mixture was placed in a sealed tube at
to water and ether extracted. The extracts were combined, washed with NaHCO,aq and water, dried
(MgSO,) and evaporated to give a oil which showed one spot on TLC and a single peak on VPC
NMR (r): formyl 5.55 H-C--O--),
in a vacuum dessicator for
hr. gave
acetate crystals (100 mg) m.p. 84-85”
(4 mg of 38%
for 18 hr then added
column F at
9.17,
1730 1175 s cm
(4 singlets, 4Me). (P)’ 318.
(19; mg) was
with HCOOH
(1 ml) for 1 hr. The mixture was neutralized with 10%
aq and ether extracted. The extracts were
combined, water washed, dried
and evaporated to give (23; 50
and NMR identical with those of the sample prepared above.
Hydrogenation
with (30 mg) under 70
supematant evaporated to give
This product gave a positive tetranitromethane test and a mass spectrum which possessed no peak at
A
of
for 4 days. The catalyst was removed by centrifugation and the
(32; 46 mg) as white solid (c =
(48 mg) in
(3 ml) was shaken
m/e = 272. NMR
Formic acid
9.27,
3Me). 9.26
= 6
Me). (P)’ = 274.
(880 mg) in 97% HCOOH (10 ml)
and etha
extracted. The extracts were combined, water washed, dried (MgSO,) and evaporated to give brown oil
A
of
was refluxed for 6 hr. The mixture was poured into water (100 ml), neutralized with
(806
benzene in pet. ether eluted
(20; 7 mg). Elution with 5% benzene in pet. ether gave a mixture
by prep. VPC on column D at 150” to give (17; 34 mg) (P)’
Preparation of sandaracopimaradiene methyl sandaracopimarate. Sandaracopimaric acid, supplied
which 680 mg was chromatographed on silica gel impregnated with 10%
g): 3%
(21; 27 (c =
272, and
mg)
by Professor J. W.
m.p.
characteristics reported for this compound.
(130 mg) was converted to methyl sandaracopimarate (103 mg)
63-64
and thence to sandaracopimaradiene”’ which possessed spectral
Dr. Edwards kindly supplied a tracing of the vinyl pattern
with
of an authentic sample of sandaracopimaradiene for comparison.
Preparation of
Pimaric acid (Koch Light) was converted to
by the same sequence described for the preparation of sandaracopimarad’ene.
(3D) enantio-copoldehyde
added with stirring to ice-cold anhyd. pyridine ml) during 10 min. A
in anhyd. pyridine (20 ml) was added in one portion whereupon the
continued for hour and at for hr. The mixture was poured into water (11) and ether extracted.
The extracts were combined and evaporated to a few ml The residue was dissolved in ether, washed with
(3.9
x
moles) was
Preparation of
of
(3.868 g)
darkened. Stirring at
was
2%
mixture of
aq, water, 2%
and enantiocopaldehyde (25; 2995 g)
aq, again with water, then dried (MgSO,) and evaporated to give a
1678 NMR 0.13 = 8
mixture),
H approx,
is actually two superimposed doublets at 007 and
= 8
vinyl Me,
Enantio-methyl
and freshly
aldehyde proton,
C-17 vinyl), 7.87
C-14 vinyl),
C-17 vinyl). 5.55
= 1
9.21,
= 1 Hz,
of
H approx, vinyl Me, cis-isomer),
(25) (446 g)
(26). A
in
(4.13
(1.52
ml) was stirred at
for 12 hr.
was removal by
tion and the
evaporated to give an amber solid which was dissolved in water and ether. The aqueous
layer was extracted several times with ether and the ether extracts combined, washed with
and water, dried (MgSO,) and evaporated to give a mixture of and
aq
copalate (26)
previously
(3.868 g)
exchange of enantio-methyl
A solution of
copalate (2.533 g) and
(3.7 in
(250 ml) was stirred at
for then evaporated to dryness at 40”. The residue