Tehahcdron Letters. Vo131, No.36, pp 5217-5218.1990 Ritcd in Great Britain

oo4o-4039/90 $3.00 + .oo Pergamlnl Press plc

INDOLE DIHER FROM MURRAYA GLENIEI ROOT

Vijaya Kumar, * D. B. Mahinda Wickramaratne and Ulla Jacobsson D

Department of Chemistry, University of Peradeniya, Peradenfya, Sri Lanka

and g Department of Organic Chemistry, Royal Institute of Technology,

S 100 44 Stockholm, Sweden.

Abstract: Hethyl 2-aethyl-4-~?$2w$-methyl-l “, 2”, 3”, 4”- tetrahydro-

carbarol-1 “a-ylfndol-3’-yl>butanoate, a novel indole dimer has been

isolated from Murraya gleniei root timber.

Strong implantation activity shown by the indole dimer, yuehohukenel

from Murraya roots has evoked interest in such dimers. We report the

isolation and structural elucidation of an indole dimer (1) with a novel

E-tetrahydrocarbazol-l-ylindole structure from iY. glenief root. Unlike

yuehchukene which contained no functional groups, 1 was a methyl ester.

The dimer (32 mg) was isolated as a gum, CalD -7.5O, from the CH2C12

extract (12 g) of the root timber (600 g). Its UV spectrum was typical of

indoles, while its IR spectrum showed that an ester group was present. 2

Molecular formula, C27H30N202 and peaks 2

at m/r 164 (C13H14N from HRMS)

and 231 (Cl4 17 2 H NO ) suggested it was a diner of indole units with C5 side

chains as in yuehchukene. One indole unit in 1 however contained the ester

group. The monomer indoles with isoprenoid substituents at 3-position have

been previously isolated from nurraya species. 3

'H NMR data4 indicated the ester to be in the form of a COOMe and that

all the indole benzene ring positions were unsubstituted. The indole N-H

and 2-H signals at d 7.96 and 6 6.03 were each due to a single proton. One

indole nitrogen and a C-2 position in I must therefore be substituted. The

only signal between b 3-O-6.5, other than the COOMe singlet. was a 1H

doublet at 6 5.20 (J=Q.l Hz). This suggested that the substituent on the

nitrogen was a -CHCH- group. Multiplets between 6 1.65-2.95 for 1OH due to

two sets of -CH2CH2CH- protons and two methyl doublets at b 0.96 and 1.19

showed that two -CH2CH2CHMe moieties were present. This was confirmed by

H-H HomoCOSY and decoupling experiments, which also showed long range

coupling between the NCH proton and the indolyllc CH2 in the sidechain at

3-position. One of the -CH2CH2CHMe group must carry the COOMe and the

5217

5218

40 COOMe

(1)

other, the NCHCH- group. The C-5’ of

the side chain in the non-oxygenated

indole unit was therefore cyclised

at C-2 and bound to the nitrogen of

the second indole unit.

The dimer should therefore be

methyl P-methyl-4-(F&-2”$-methyl-

lW,2n,3”,4”-tetrahydrocarbazoI-lWu-

ylindol-3*-yl)-butanoate (I). The

CHCH coupling constant showed the

stereochemistry of the substituents

on the tetrahydrocarbazole ring to

be trens-diequatorial. Relaxation

times (Tl) of the CH3 protons at

6 Q.D0 and 1.19 were respectively

0.53 and 0.83 s suggesting that the

5 0.98 signal was due to the ring methyl group. Models show that the only

other structure with an NCHCHHe-, in which C-5’ would be cyclised at

nitrogen and bound to C-2 of the second indole cannot physically exist.

The I3 C-NMR spectrum5 of 1 was assigned by comparison with those of

indole monomers and by DEPT and C-H HeteroCOSY experiments.

Acknowledgements: Ye thank the International Foundation for Scfenoe, Stockholm, Sweden and

Cfba-Geigy, Basle, Switzerland for financial assistance.

References:

1. Y. C. Kong, K. F. Cheng, R. C. Casbie and P. G. Watersan, J. Chem. Sot. Chew. Commun.,

45 (1985).

2. uv x : 222, 271 and 204 ns; IR “sax : 3400 and 1730 os.-I; US: 414 (IQ), 231 (13), sax. .

100 (271, 184 (100) and 130 (47).

3. T. Kinohita, S. Tatara and U. Sankaua, Chem. Pharm. Bull. Japan, 33, 1770 (1085) :

D. 8. Ii. Vickrasaratne and V. Kusar, Abstract ASOHPS VI, Bandung, P3-3 (1060)

4. ‘H-NIIR (400 MHz): 6 0.06 (d, J=6.6 Hz, 2”-tle), 1.19 (d, 5~7 Hz, 2-lIeI, 1.85 (B,

wti=40 Hz, 3-and 3*-H), 2.10 (m, w5=47 Hz, 3- and 3”-HI, 2.50 (e, ud32 Hz, 2- and

2*-H), 2.75 (dt, J=l5 and 7.2 Hz, 4-H), 2.79 (dt, 5115 and 8 Hz, 4-H), 2.92 (dt,

J=2 and 4.1 Hz, 4”-H), 2.03 (ddd, 5~5, 2 and I.8 Hz, 4*-H), 3.33 (s, One), 5.20 (br.d,

J=Q.l Hz, In-H), 6.83 (br.s, x%=5.5 Hz, 2.-H), 7.08-7.21 (s, x5=35 Hz, 5’-,6’-,7’-,

6”-,7”- and en-H), 7.58 Is, wQ=31 Hz, 4’- and 5*-H) and 7.08 (br.6, t/Q=12 Hz, NH).

5 . 13C-NHR (100 MHz): 6 17.0 (2-He), 19.0 (2”~Me), 20.5 (4”~C), 22.0 (4-C). 31.4 (3”-C),

33.8 (3-C), 36.9 (1*-C), 38.8 (2”~C), 30.4 (2-C), 51.3 tOtIe), 111.2 (7’- and 8”-C),

112.8 (4a”-C), 114.6 (3*-C), 116.6 (5*-C), 110.3 (4’~C), 110.4 (7”- and 6’-C), 121.7

(6”~C), 122.0 (5’~Cl, 127.0 (3a’-C), 128.3 (2’~C), 128.6 (5a”-0, 130.0 (law-C), 132.6

(8*-C). 136.5 (7a'-C) and 177.2 (CO).

(Received in UK 3 July 1990)