Indian Journal of Chemistry Vol. 388, July 1999, pp. 877-88 1

Note

New pentacyclic triterpenic esters from the roots of Calotropis gigantea

Mohd Ali* & Jyoti Gupta

Faculty ofPharrnacy, Jamia Hamdard (Hamdard University) , P .O. Hamdard Nagar, New Delhi 110062

Received 15 December 1998; accepted (revised) 3 May 1999

Phytochemical studies on the roots of Calotropis gigantea resulted in the isolation of one new lupene type triterpene identified as lup-1 3 ( 18), 19 (29)-dien-9a-yl acetate and lupeol acetate and two new ursane type triterpenes characterized as urs- 18~-H-12 ,

20(30)-dien-3~-yl acetate and 1 7~-hydroxy-28-nonnethy l urs- 18a­H-12, 20 (30)-dien-3~-yl acetate on the basis of spectral data analyses and chemical reactions.

Calotropis gigantea (Linn .) Ail. f. (Asclepiadaceae) is a much- branched, hardy , erect and wooly shrub found growing up to an altitude of 900 m throughout India. Its roots resemble Ipecac in properties and act as diaphoretic, stimulant , expectorant, carminative and cardiotonic. They are useful in leprosy, eczema, syphilis , e lephanti as is, mecurial cachex ia, ulceratio~ ,

cough, asthma anacara and stomachal di sorders. Some pentacyclic triterpenoids have been reported

. ?-S TI t from the roots of Calotropis spec les-·. le presen paper describes the isolation and characterizati on of three new pentacyclic triterpenic esters from the root of the plant.

The ethanolic extract of the root bark on column chromatography over s ili ca ge l furnished compound 1 in petroleum ether e luant . Elution of the column with petroleum ether-chloroform (9: I , 3: I & I : I) afforded the compounds 3, 6 and 9. These compounds responded positively to the Liebermann Burchard reaction.

Compound 1, named calotroplupenyl acetate A, positive JI1 Burchard-Liebermann test; had a molecular ion peak at mlz 466 in its mass spectrum corresponding to C32Hso02. Its IR spectrum showed bands at 1725 cm-I for acetoxy group and at 1615 cm- I for unsatruration. The IHNMR spectrum lacked

any vinylic proton signal beyond 8 5.0 suggesting tetrasubsitituted olefinic linkage in the molecule_ It di splayed broad signals for terminal methylene grQup

1

2

6

7

8

9 1 0 11

3

R = OAe

R = OH

R, = P-OAe, H, R, = P-OH, H, R, 0 , R, =CH) R, p- OAC, H, R, P-OH , H , R, 0 , R, =OH

R, =CH,

R2 =CH ,

R, =OH

R, =OH

at 84.63 (2H,CH2-29), an acetyl group at 8 2_03, one

methyl group attached to unsaturated carbon at 8 1.80 (Me-30), and six methyl s located at saturated carbons at 8 1.06 (Me-27) 1.00 (Me-25) ,0.96 (Me-23), 0.90 (Me-24, Me-28) and 0.87 (Me-26). The absence of

any methine proton s igna l in between 8 4.50-3.00 re fl ected the tertiary naiure of the acetoxy group . From these evidences it was conc luded that the compound 1 was a new pentacycli c triterpenoid acetate with a lupene type carbon framework containinng a te trasubstituted bond in ring DIE, and one unconjuO'ated exocyclic methylene groups.The

b I f ' . b did t A 11( IS ) . tetrasubstituted 0 e II1IC on was p ace a ti JI1

the lupene skele ton on the basis of following mass fragmentation pattern . The intensified fragments at mJz 216 and 250 were generated by c leavage of C9- 11

and C8- 14 bonds with a charge retent ion on either

878 INDIAN J. CHEM. SEC B, JULY 1999

fragment6.7 . Besides the normal cleavage of ring C,

the ~13(I S) bond migrated to ~12 due to electron impact

which then underwent retro-Diels-Alder frag­mentationS leading to rnIz 203 . This type of migration is not possible in ~S(9) or ~17(I S)

tetrasubtituted linkage. Formation of the highly intensified peak at rnIz 188 involved the cleavage of C 12(I3) and CS(14) linkage accompained by trasnfer of hydrogen from C-I7 to C- I 2 and migration of the double bond to C-I4. A peak at rnIz 406, formed due to elimination of mass unit 60 (HOAc) from the molecular ion peak, disclosed the presence of acetaxy group in the molecule. The ion framents at rnIz 97, 83 [97-CH2r, 69 [83-CH2r, 69[83-CH2r , 124 and 138 (C9/iQ-C6n fission) supported the absence of acetoxy groups in rings A and B. The ion fragments at rnIz 216 and 250 supported the existence of the acetoxy groups at C-9. The ion fragments at rnIz 188, 278

[CI 2113-CI3IWCISI1 6 fi ssionr, 189 [CI 2IIrCI3IWCI S/16

fissionr and 82, 384 [CI 811 9-C I7I22 fi ssionr also indicated the presence of tetrasubstituted bond at ~1 3( IS) .

Alkaline hydrolysi s of the acetate 1 furnished a free alcohol, calotrolupenol A 2, [IR (KEr) : 3410 cm-I

) . The alcohol could not be oxidized with Jones reagent further indicating the tertiary nature of the hydroxyl group in 2, hence acetoxy group in 1.

On the basis of these evidences the structure of the natural product calotroplupenyl acetate A 1 has been

formulated as lup-13 (18), 19 (29) dien-9a-yl acetate and reported for the first time.

Compound 3, lupeol acetate B, positive in Liebermann- Burchard test, had molecular ion peak at m/z 468 corresponding to C32Hs20 2. Its IR spectrum showed the presence of ester group (1725 cm- I

) and unsaturation (1610 cm- I) . The 'HNMR spectrum of 3 displayed a broad signal for two olefinic protons at

() 4 .76 assigned to C-29 methylene group, a one­

proton double doublet at () 3 .50 with coupling interactions of 4 .5 and 9 .0 Hz ascribeable to the axial C-3 methine proton and a three-proton broad signal at

() 2. IO due to acetoxyl methyl group. Among seven methyl functionalities appeared as broad singlets at

() 1. 13 (Me-27), 1.03 (Me-26) , 0 .97(Me-26), 0.93 (Me-24, Me-25) and 0 .90 (Me-28), one methyl was

located at olefinic carbon-20 and resonated at () 1.53 (Me-30).

Electron impact mass spectrum of 3 exhibited the presence of typical ion fragments of high intensity at

rnIz 408 [M-AcOHr and at rnIz 250 and 218 generated due to cleavage of ring C. The base peak at rnIz 189, formed due to fission of C l2llrCSI14 bonds, ruled out the presence of ~1 2 olefinic linkage and indicated the lupene-type carbon frame work of the molecule.

Alkaline hydrolysis of 3 yielded lupeol. Based on these evidences the structure of 3 has been e luc idated

as lup- I 9(29)-en-3~-yl acetate.

Compound 6, designated as gigantursenyl acetate A, positive in Liebermann-Burchard test, had molecular ion peak at mlz 466 corresponding to C32Hso0 2 .. Its IR spectrum showed absorption bands for acetate group (1735 cm-I) and unsaturation ( 1590 em-I). The 'HNMR of 6 di splayed a vinylic proton

signal as a multiplet at () 5.16 ass igned to H- I 2, an

exocyclic methylene signal at () 4.50 (m) ascribed to Hr 30, a carbinol proton signal as a double doublet at

() 3.40 with coupling interacti ons of 4.0 and 8.5 Hz,

associated with H-3a and a broad s ignal at I) 2.8 1 (WY2 = 12.0 Hz) suggesting that the compound was of

ursane series containing 1 8 ~-hydrogen. Six terti ary methyl functionalities appeared as broad signals at () 1.03 (6H, Me-23, Me-27), 1.00 (3H. Me-26), 0 .83 (6H, Me-25, Me-28) and 0 .79 (3H, Me-24). The acetyl and C-29 secondary methyl groups resonated

as a broad signalet at 82.06 and as a doublet at I) 0 .96 (1=6.0 Hz) , respectively. The remaininng methine and

methylene groups apreared in between () 1.98 to 1.36. The I3C NMR spectrum of 6 showed ::n carbon atoms in the molecule containing one ester, four o le finic and one carbinol carbons.

Electron impact mass spectrum of 6 exibited important ions associated with amyrins. The ion peaks at rnIz 249 and 216 corresponded to the typical retro-Diel s-Alder fragmentati on of ~ 12 pentacyc l ic skeleton at C9/ 14 and CSI1 4 bonds6

. Thi s was supported by the daughter peaks at mJz 20 I [2 I 6-Mer, 189 [249-HOAcr and 174 [I 89-Mer . Another important ion fragments of significant importance appeared at rnIz 450 [466-Mer, 406[466-HOAcr. 390 [406-Mer, 339, 126 [C2I3-C5110-C6n fi ss iont , 84 [C2WC 511 0-

C I4115 fis sionr, 84 [CIIIO-C4/5 fi ssiont, I 38 [CJIIO-C617

fi ssiont,150 [CI 3I1S-C I4I15 fi ssiont, 136 [C l3m -CI 511 6

fi ssiont and 122 [CI 3I1 S-CI 6117 fi ss ion]+ These data suggested that the acetate group was attached to ring A which was placed at C-3 on the basis of biogenetic consideration. Treatment of the compound 6 with alcoholic KOH at reflux temperature yielded a

NOTES 879

deacetylated product g igantursenol A 7 (IR: 3405 cm-I

). Jones oxidation of 7 afforded an ox idized product gigantursenone A (IR: 1705 cm· l

) which gave

positive Zimmermann tes t 9 indicating the presence of 3-oxo group . On the basis of these informations the structure of gigantursenyl acetate A 6 has been

formulated as urs- 18~ -H- 1 2, 20(30)-dien-3~-yl

acetate. Thi s is also a new triterpenic ester of ursenyl series.

Compound 9 , named gigantursenyl acetate B, positive in Liebermann-Burchard test, had a molecular ion peak at mlz 468 in its ElMS corresponding to C31H4S0 3. Its IR spectrum showed the presence of hydroxy group (34 10 cm-I), ester group (1725 cm-I), and unsaturati on ( 1600 cm-I). The presence of three bands in the region 1450-1365 cm-I

and two bands in the region 1330-1240 cm·1 indi cated that the compound was probably an ursane-type triterpene.

The compound 9 cound not be acetylated with acetic anhydride-pyridine mixture di sclos ing tertiary nature of the hydroxyl group. The IHNMR specturm

of 9 exhibited a one-proton multiplet at 8 5.16 assigned to a vinyl ic C-12 proton, a two-proton broad single t ascribed to C-30 exocyclic methylene group, a

one-proton double doublet at 8 4 .36 with coupling interactions of 4 .5 and 9.5 Hz due to H-3 ax ial

methine proton, one doublet at 8 2.73 (.1=2.5 Bz)

attributable at 18 a-proton and a 3-proton broad

singlet at 8 2.00 associated with the acetoxy group. The five tertiary methyl groups, resonated as broad s ingle ts at 8 1.20 (Me-27) , 1.06 (Me-23), 0 .86 (Me-26, Me-25), and 0 .80 (Me-24). An upfie ld three­

proton doublet at 8 0 .96 (1=6.0 Hz) was ass igned to C-29 methyl group . The re maining methine and

methylene functionalities appeared in between 82 .20 to 1.23 . These data suggested that the compound 9 was an acetate containing a 28-nortriterpenoid skele ton of ursane seri es with a tri substitited double bond . The 13C NMR spectrum of 9 showed 31 carbon atoms in the molecul e containining an ester, four

olefinic and two carbino l (880.8, 79.3)carbons.

Mass spectrum of 9 di splayed important ion peaks at mlz 450 [M-H20t, 408 [M-HOAct, 82 [CI .IO-C 4.5

fission-AcOHt, 150 [C).IO-CU fis s ion-AcOHt, J 36 [150-CH2t , 122 [I 36-CH2t, J24 [C I6.17 -C lg.13 fis­siont, J 06 [J 24-H10t and J 09 [J 24-Met. The base peak at mlz 2 18 and another peak at mlz 250 were characteristic of the re tro-Oie ls-A lder fragmentation

of ring C of a pentacyc lic trite rpene with a ~I l double bond6

.7. Elimination of mass units 15 [Met, from 2 18

and 60 [HOAct · from 250 gene rated the ion fragments at mlz 203 and 190, respec tive ly. Wealth of the structure was obtained from de ri vati zat ion of the compound 9. Alkaline hydro lys is of 9 yie lded a diol , gigantursenol 10, [IR (KBr): 34 10, 3380 c m (OH)]. Oxidation of 10 with Jones reagent produced oxo­deri vative, gigantursenone, 11 , [IR (KBr): 3375 (OH), 1710 <.:m- I (CO)]. The compound 11 responded positive ly to Zimmermann test') indicat ing the presence of 3-oxo deri vati ve. On the basis of these spectral and chemical evidences the structure of g igantursenyl acetate B 9 has been establi shed as 17

~-hydroxy-28 - nonnethylurs- 18 a H- 12,20nO)-dien-

3~-yl acetate. Thi s constitutes the first report of the presence of 28-desmdhyl triterpeni c es ter of ursenc­series possess ing a hydroxy l group at C- 17 .

Experimental Section General. Melting po ints were dete rmined on a

Perfit melting point apparatu s and are uncorrected. IR spectra were recorded on KBr pellets us ing Perkin Elmer 88 1 instrument. UV spectra were scanned in methanol on Hitachi 120-50 model. IHNMR (300 MHz) spec tra were run on Varian T300 A instrument in COCl3 with TMS as an internal standard . EI mass spectra were recorded on a Jeo l 0-300 spec trometer at 70eV, CC was run using s ili ca ge l (60- 120 mesh). TLC was run on silica ge l G in so lvents C(,H(',C ,H6-

CHCI3 (3: I, I : I, 1:3), CHCI , and CHCl 1-MeOH ( I :9, I :4). Iodine vapours, ceric ammonium sulph ate and UV light were used for visualization of TLC spots .

Extraction. Ori ed and coarsely powdered roots (3kg), collected from Oasna (Ghaziabad ). were exhausti ve ly ex tracted with ethanol (95 %) in a Soxhlet apparatus. The extract was dri ed i ll VUClIO

yielding a residue ( 125 g) . The crude ex tract was subj ec ted to silica gel co lumn c hromatography usi ng pet. e ther, CHCI, and methanol as so l vent s in the order of gradient increment of polarity.

Lup-13(18),19(29)-dicn-9a-yl acctatc 1. Eluti on of the column with pet. ether furnished 1. crysta lli zed from MeOH, 60 mg (0.002%), mp 178-

80ne. [a];o + 11.5°(CHCI" 0.2): UV (McO H): 265 nm

(log £ 3.8); IR (KBr): 2910. 2850. 1725. 161 5. 1465. 1245, 1090, 1025 , 101 5. 990. 880 CI11 -

I. IH-NM R

84.63 (2H, brs, C H2-29), 2.50 ( I H, m, C H). 2.13 (2H, m, 2xCH), 2 .03 (3 1-1 , brs, CaCH,), 1.80 (3 H, brs, Me-

880 INDIANJ.CHEM.SECB, JULY 1999

30), 1.67 (5H, m, CH, 2xCH2), 1.50 (4 H, m, 2x CH2),

1.46 (2H, m, 2xCHz), 1.36( I OH , brs, 5xCHz), 1.06 (3 H, brs , M e-27), 1.00 (3H, brs, Me-25), 0.96 (3 H, brs, Me-23), 0 .90 (6H, brs, M e-24, Me-28), 0.87 (3 H,

brs, Me-26); ElMS (re I. in t. ) : mlz 466 [Mt (Cn Hso0 2) ( 10.6), 406 (9. 6), 397 (4.2), 392 (4.2), 384 ( 1.2), 278 ( 1. 1), 264 (4.3) , 250 ( 1. 2), 249 ( 10.5), ] 16 ( 16.7), 203( 16 .8), 189 (26.0), 188 (78.8), 175 (21.2) , 16 1(16.2), 147 ( 10.6), 138 ( 11 . 1), 133 ( 19.4) 124 (22. 1), 97 (7 .2) , 87 (24.0), 84 ( 18.5), 83 ( 10.3), 82 ( 10.4),73 (40.0), 69 (40. 1), 68 ( 11.2), 55 (48.9).

Alkaline hyd rolys is of 1. Compound J ( 10 mg) was heated with 5% ethano li c NaOH so lution for 1 hr. T he reacti on mixture was ex trac ted wi th CHCh

(3x I 0 mL). The o rgani c phase was was hed with

water (2xS mL), dri ed over Na2S04 and evaporated to

get the free a lco ho l, 2 , mp 205-06ue. 1R (KBr): 34 10 · 1 cm .

Lupeol acetate 3. E luti on of the column w ith pet. e the r-CHC b (9: I) furni shed co lourless amorph ous

powder o r 3 , rec rys ta lli zed w ith MeOH , 100 mg

(0 .0033 %) , mp 2 16- 18°e. [a ]~o +46.5 (CHCI}, 0.02) ,

U Y (MeO H) : 270 nm ( log £. 4.5) ; IR (KBr): 1725 , 16 10, 1460 , c m· l

; ' HNMR : 84.76 (2 H, brm, CH2-

29) , 3 .50 (l I-J, dd, J=4.5, 9.0 Hz, H-3a.), 2 .50 ( I H,

brm, H-I S), 2 .1 0 (3 H, brs, COCH1) 1.53 (3 H, brs, Me-30), 1.13 (3 H, brs, Me-27), 1.03 (3H, brs, Nle-23), 0 .97 (3 H , M e-26), 0 .93 (6H , brs, Me-24, Me-25) , 0 .90 (3H , brs, Me-28); E lMS (re I. in L): mlz 468 [Mt (C }2H520 J ( 13 .S), 453 ( 1. 2) , 408 (9.6), 393 (6.0),250 ( 13 .8), 21 8 (2 1. 1), 204 (23. 1 ), 203 (13 .2) , 19 1 (32 .9) , 190 (37 .8), 189 ( 100), 177 ( 10.7) , 163 ( 14 .6) , 150 (23.5), 136 (36. 1), 122 (60.7) , 109 (60 .9) , 95 (79.5 ), 82 (68.7), 68 (70.4), 55 (65 . 1), 43 (99 .8).

Alkaline hyd rolys is of 3 . C(lmpou nd 3 (50 mg) was re flux e c! w ith 0.5 N e tha noli c N,OH solution ( 10 ml ) fo r 5 hI'. The react ion mixure was extracted wi th

C HC r.1 (3x 1 0 mL). T he o rganic ph ase was washed

with wate r (2x5 mL), dr ied (Na2S0 4) and evaporated to y ie ld lupco l 4, mp 2 12- 14"C; 1R (KBr): 3400 cm·

l;

IH-N M R (C DC 13): 8 4.66 (2 H, m, CH 2-29), 3 .26 ( I H,

dd , J=5.0, 9.0 Hz, H-3a.), 1.60 (3H. s, Me), 1. 10 (3H ,

s, Me) , 1.0 -1- (3H , s, M e) , 0 .96 (6H, s, 2x Me), 0 .90

(6H, s, 2x Me).

Urs-18~ -H - J2,20 (30)-d ien -3~ -yl acetate tl. Pet. ethe r-CHCI) (3 : I) e luants o f the co lumn on crys ta lli za ti on from C HC I1-MeOH ( I : !) y ie lded white amorphous powder of 6 , 145 mg (0.0048 %),

mp 175-77°e. [a.]~o +21 .5° (CHCI}, 0.3); UY (MeO H):

238 nm (log £. 5.0) ; IR (KBr): 2945, 2860, 1735, 1590, 1455 , 1380, 1360 , 1240, 970, 925, 87:'i C Ill·

I;

'H-NMR :85 . 16 ( I H, m, H-1 2) , 4.50(2H , Ill, CH z-30),

3.40 ( I H, dd, J=4.0, 8.5 Hz. H-3a.). 2.8 1 ( 11-1 , brs ,

wY2= 12.0 Hz, H-1 8~), 2.06 (3 1-1 , brs. COCt-h, 1.90

(2H , brs, 2xC H), 1.83 (4 1-1, brs , 2x Cl-l z), 1.70 ( 11-1 , Ill.

CH) , 1.66 (4H , brs, 2xC H2) , 1.53 (6 H, brs. J x C H]) .

1.36 (4H , brs, 2xCH2), 1.03 (6H , s. Me-n, Me-27 ), 1.00 (3 H, s, M e-26) , 0 .96 ( I H, d, J=6 .0 Hz . Me-29), 0.83 (6H, brs, M e-25 , M e-28) . 0.79 (31-1. brs. Me-24);

EIMS (re I. int.): mlz 466 [M t (Cl1 1-1 5002 ) ( 1.9), 450 ( 10 .5), 406 (4.0) , 390 (2.6), 352 (3. 5 ), 339 ( 13 .6), 296 ( 10.4),282 ( 10.6), 270 (3 . 1), 256 n. 7). 249 n.O). 2 16 (95.8),20 1 (4 1.9).1 89 (10.2 ). 188 (30. 1), 175 (J.I ),

174 ( 15.7) , 160 ( 16.3 ), 150 (2. 1), 146 ( 17 .5 ), 138 ( I.! ), 136( 16.7) , 134 (28.9) , 126 (2 . 1), 124(2 1), 122

( 17 . 1), 120 (29.9), 11 2 (29 .8), 109 n :U ), 95 (43 . 1),

84 (20 . 1), 43 ( 100) . I.1C NMR : 8 38.5 (C- I). 13.2 (C-2), 80.6 (C-3) , 38. 1 (C-4) . 54.9 (C-5 ), 17 .9 (C-6 ),

34.2 (C-7), 40.4 (C-8), 48 .2 (C-9), 37. :' (C- IO). 23. 1 (C-II ), 123.8 (C- 12) , 140.1 (C-I:' ). 4 1.7 (C- 14) , 27. 8 (C- 15), 26 .3 (C-1 6 ), 36 .7 (C- 17 ), :'i0 . 1 (C- 18). 39 .6 (C-19), I :'i2.9 (C-20) , :n .5 (C-2 1). :'8 .7 (C-22). 26 . 1 (C-23), 15.9 (C-24) , 14. 1 (C-25 ). 16 .) (C-26 ). 25.1

(C-27), 16.4 (C-28) , 19 .2 (C-29 ), 106 .8 (C-:,O ), 170.7. 21. 1 (OAc).

Alka line h ydrolysis of fl. T he co mpound tl (50 mg) was reflu xed w ith /I 0 e th anolic KOH (20 mL) for 4 hr. The reacti on mi xture was cxtractcd w ith

CHC I1 OX I 0 mL) , the organic phase was hed w ith

water (2x I 0 mL), d ried (Na"S04) and evaporat ed to

yie ld the deacety lated produc t. g igant ursc nol A 7 : mp 192-1 93"C ; lR (KBr): ]405. :29 10. 1590 . 1450. 135\ 1020 , 895 CI11-

I.

Jones oxidation of 7. Co mpound 7 ( I () Ill g.) was disso lved in ace to ne (1 0 Il1L ) and treated w it h freshly prepared Jones reagent (:2 IllL). Th e reac tion mixt ure was stirred at roo m te mpe rature t ill the compl e ti on of the reacti on (TLC monito ring). It was d ilu ted w ith wate r and extrac ted w ith so lve nt e the r. The e lhe r laye r was washed \vith wate r, dl ied ( , [;\ 2- 0 4 ) and evaporated to d ryness to yie ld 3 - 0.'\0 dcri \';lt ivt: ,

gigantu rsenone A 8 , I1lp llO-II "e: IR (KB I') : 2<) 10 . 1705,1 600,1 45 5. 138 'i C lll -

i.

17(i . Hydroxy-28-nomlethyI1ll· '- ISal l-12. 20(3())­

dicn-3~·yl aceta te 9. E luti on of the COI U Ill I1 Wi th pet. e the r-CHC I, ( 1: i ) fU l'l1i shed wh it e c rystah or y, rl' ­

c rysta llized with C HCI1-MeO I-l ( I : I ). .230 n lg

NOTES 88 1

(0.0076%), mp 180-81 DC. [a]~o +46.7°(CHCI" 0.03) ,

UV (MeOH): 265 nm (log E 6.5); IR KBr): 3410, 2910, 1725, 1600, 1450, 1380, 1365, 1320, 1240, 1025,980,870 cm'l. IHNMR: 05.16 (lH, m, H-12) , 4.63 (2H, brs, CHr 30), 4.36 ( I H, dd, J= 4.5, 9.5 Hz, H-3a), 3.60 (I H, brs, D20 exc hangeable OH), 2.73 ( 1 H, d, J=2 .5 Hz, H-18a), 2.20 ( I H, m, CH), 2.10 (3 H, brs, CH, CH2 ), 2 .00 (3 H, brs, COCH,), 1.60 (7H, brs, CH, 3xCH2), 1.50 (4H, brs, 2xCH2) , 1.23 (6H, brs, 3xCH 2), 1.20 (3H, brs, Me-27), 1.06 (3 H, brs, Me-23), 0.96 (3 H, d, J=6.0 Hz, Me-29), 0.86 (6H, brs, Me-26, Me-25), 0.80 (3H, brs, Me-24); EIMS (reI. int.) : mlz 468 [Mt (C, I H4SO,) ( 14.1), 450 (6 .6), 408 (9 .6), 398 ( 1.0), 398 ( 1.0), 392 (6.0), 356 (2. 1), 277 (2.3), 270 (6.4), 264 ( 1.3), 256 (7.8), 254 (7.6), 250 ( 12.8), 2 18 ( 100), 204 ( 12.0), 203 (26.9), 190 ( 14.3), 177 (4.5), 175 ( 10. 1), 163 (9.8), 161 ( 10.7), 150 (3. 1), 147 ( 11 .8), 136 ( 12.2), 126 (2.3) 124 (10.9), 122 ( 15 .2), 11 2 (8. 1), 109 (2 1.3), 106 ( 11.6), 95 ( 18.3), 82 ( 15 .3), 70 ( 17 .9), 56 ( 19.2), 43 (32.0); DC NMR:o 37.6 (C-I ), 23.5 (C-2), 80.8 (C-3), 39.6 (C-4), 55.2 (C-5), 18.0 (C-6), 34.4 (C-7), 40.7 (C-8), 48.6 (C-9), 37.6 (C-IO), 23.6 (C-I 1), 124. 1 (C- I·2), 139.4 (C-1 3), 4 1.9 (C-14), 27.2 (C-15), 26.5 (C-16),79.3 (C-17), 50.3 (C-1 8), 39.8 (C-1 9), 154. 1 (C-20), 33.9 (C-21 ), 38.5 (C-22), 26.0 (C-23), 16.3 (C-24), 14.5 (C-25), 16.3 (C-26), 25.3 (C-27), 16.1 (C-28), 19.4 (C-29), 107.1 (C-30), 170.7,2 1.1 (OAc) .

Alkaline hydrolysis of 9. Compound 9 (60 mg) was refluxed with 5% alcoholic NaOH so lution (20

mL) for 4 hr. The reaction mixture was extracted with CHCI, (3x 10 mL). The organic layer was washed with water (2x 1 0 mL), dried over Na2S0~ and evaporated to get the free alcohol gigantursenol B 10; mp 196-97DC; IR (KBr): 34 10, 3380, 29 15, 1590, 1455, 1380, 1245, 1025 cm' l.

Jones oxidation of 10. Gigantursenol B 10 ( 10 mg) was disso lved in acetone (20 mL) and treated with freshly prepared Jones reagent (5 mL). The reaction mixture was stirred at room temperature till the reacti on was completed (TLC monitor ing). It was diluted with H20 and ex tracted with Et20. Removal of the solvent from the EtlO ex tract yie lded gigantursenone B 11, mp 98-99"C; IR (KBr): 3375, 2905, 1710, 1595, 1460, 1385 cm' l.

References 1 Nadkarni A K , Ilidioll 1I1{{lerio III cc/im (Popular

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