P H Y T O E C D Y S O N E S O F S e r r a t u l a

IIIo MASS SPECTROMETRIC STUDY OF THE ACETATES AND ACETONIDES

OF ECDYSTERONE AND VITICOSTERONE E

I . L . Z a t s n y , M. B . G o r o v i t s , Y a . V . R a s h k e s , a n d N. K. A b u b a k i r o v

UDC 543.51 +547.926

We have studied the mass spec t ra of some acetates and acetonides of ecdys te rone and vi t tcosterone E and have also compared them with the spec t ra of analogous der ivat ives of ecdysones not containing ahydroxy group at C2s [1]. In view of the identical nature of the f ragmentat ion of the s teroid nucleus, the main dif- fe rence of analytical value in the m a s s - s p e c t r o m e t r i c behavior of these two se r i e s of compounds is con- nected with the nature of the decomposit ion of the side chain.

For ecdys te rone (I) the predominating p roces s is the cleavage of the C20-C2z bond, leading in the final account to the appearance of two strong peaks with m / e 99 and 81 [2] (Scheme 1 and Table 1). The f ragment with m / e 81 is also charac te r i s t i c for a whole se r i e s of aceta tes . The other types of cleavages of the side chain of ecdys te rone are expressed considerably more feebly. However, in the mass spec t rum of (I) there is an appreciable peak with m / e 69. This ion could obviously be formed as a resul t of the spli t- ting out of a molecule of wate r at the expense of the hydroxyl at C25 followed by cleavage of the C22-C~3 bond.

The intensity of this peak rises considerably in the spectra of viticosterone E (the 25-monoacetate of ecdysterone (II)) and of the 2, 3, 22-trtacetate (Ill), while in the mass spectrum of the 2, 3, 22, 25-tetraacetate {W) the ion with role is the maximum ion (see Table 1). Decomposition of this type is not characteristic of the acetyl derivative of ponasterone A, of makisterones B and D, or of ajugasterones B and C, which have no oxygen-containing substituent at C25. No intensive cleavage of the C22-C~3 bond is found, either, for the aceta tes of makis te rones A and C, which contain an alkyI substituent at C24 [1].

~;HC L~H- C(GH3) 2 role gg

m/e eg I_H2 0 / . m/e 81

HO OR • / / t ~

RO : ,s

. - H~O; AGOH H o

~H3 / CH=-~"

CH~ CH-G-- CH-CH = GH-G- OH rn/e 152 ~ CH 3

zS=RI=H Jl R = H; R.~Ac m R=Ac; R~H Scheme 1 ,v R = R,=Ae

Institute of the Chemis t ry of Plant Substances, Academy of Sciences of the Uzbek SSR. Trans la ted f rom Khimiya Pr i rodnykh Soedinenii, No. 2, pp. 155-158, March-Apr i l , 1975. Original a r t ic le submitted October 30, 1973.

©1976 Plenum Publishing Corporation, 22 7 West 17th Street, New York, N. Y. 10011. No part o f this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission o f the publisher. A copy o f this article is available from the publisher for $15.00.

170

TABLE 1. Mass Numbers and Relative Intensit ies (~) of the Main Ions C h a r a c t e r - izing the Fragmentat ion of the Side Chain of the Acetates of Ecdys te rone and Of Vitco- s terone E

Corn- role

pound 99 z~;:~

I II

IIl IV

69 81

73

l~ 50

100 1

lOO 2 14

In the mass spec t rum of the t r i ace ta te RID, the maximum peak is that with m / e 152, obviously formed a f te r the eject ion of molecules of water and acet ic acid f rom the side chain followed by the cleavage of the C13-C17 and Cl5 -C1B bonds (see Scheme 1).

The mass spec t ra of the acetonides (V-VIII) (Scheme 2) in some acts of decomposit ion re ta in an analogy with the acetonides of pona- s terone A [1] (the f ragments of the s teroid nucleus, the e ject ion of mole- cules of acetone, ketene, etc.) but d i f fer by the decomposit ion of the side chain, which is also due to the oxygen-containing substi tuent at C~.

In the mass spec t rome t ry of the mono- and diacetonides of ecdy- s terone (V, VI), cleavage of type a (see Scheme 2) gives an ion with m/e 201, the s t ruc ture of which is confirmed by the p resence in the spec- t rum of the deuterated diacetonide of ecdys te rone of a peak displaced by six units - w i t h m / e 207.

1". °÷ CH= = CH - CH - C(CHa) £ GH~C-CH - CH i- GH=C(CHz) z

role e2 d ' role 125

÷o o

0=---C-CH~GH=C(CH31z ~"~ " ~ G H ; - C - C H - C H i - C H i - C - O H " m/e97 0 " 0 o role 201 ~ [IH 3

Ha

v B.=RFH 1 vz R=>CMe2; Ri=H bc v. R=H; R~Ao ~:,, R=>I~Mez; RFAc

c

- - 0 o i HX M - 9 9

m/e 102 i i

ITI/e 99 ~ '

J - H~O

rn/8 81 +

OH _ • _(HeO+G2HsOL -1 +"

OH rA-157 ['363(V); 403(VI):] role 300 (V) ; 340 (Vl)

Scheme 2

It is possible that the p re sence of a hydroxy function at C25 st imulates the decomposit ion of the f rag- ment with m / e 201, and the s trong peaks with m / e 99 and 102 are formed (see Scheme 2 and Table 2). The l a t t e r has an analog (m/e 108) in the spec t rum of the deuterated diacetonide of ecdys te rone . The ion with m / e 99, containing no isotopic label (no corresponding shift is observed in the spec t rum of the deuterated diacetonide of ecdysterone) , a f te r the e jec t ion of a molecule of water, gives a f ragment with m / e 81. Like other acetonldes [3], and also the diacetonide of ponasterone A [I]. the ion with m / e 201, losing molecules of acetone and water success ively , fo rms f ragments with m / e 143 and 125.

Ions with m / e 99 and 102 can also a r i se by another competing direct ion. Under the action of e lec t ron impact, the acetonides (V) and (VI), undergoing cleavage of the bc type with the t r a n s f e r of a hydrogen atom to the oxygen atom, f ragment to ions with m / e 99 and M - 99, In the diacetonide of ecdysterone (VI). the ion with m / e M-- 99 (461) cor responds to a deuterated analog with m / e 473. The fragment with m / e M - 99 decomposes with the cleavage of the CIT-C20 bond, forming an ion with m / e 102.

In the mass spec t rum of the diacetonide (VI), the maximum peak is that of the ion with m / e 403 (IV/- 157) ar i s ing by be cleavage. In the spec t rum of the monoaeetonide (V), the 100% peak of the ion with m / e

171

TABLE 2. Mass Numbers and Relat ive Intensi t ies ~ ) of the Main Ions C h a r a c - te r iz ing the Fragmenta t ion of the Side Chain of the Acetonides of Ecdys terone and Vi t icos terone E

Coin- I rnte

I I I l 122

300, which is a der iva t ive of a f r agmen t with m / e 363 (M - 157) also r e p r e s e n t s a f r agment of the s te ro id nucleus [2].

Under the act ion of e l ec t ron impact , the acetonides of v i t icos terone E (VII and VIII) decompose different ly. The main initial p r o c e s s in this case is obviously the spli t t ing off a molecule of acet ic acid and the fo rma t ion of an ion M - 60. The M -- 60 f ragment , undergoing bc c leavage with the t r a n s - f e r of the hydrogen a tom f r o m C23 to C22 gives the m a x i m u m ion, with m / e 82, in the spec t r a of compounds (VII) and {VIII). In addition, the M - 60 ion, on the decomposi t ion of the di- oxolane ring in the bd manne r with the t r a n s f e r of a hydro- gen a tom to the s te ro id f ragment , f o r m s a fa i r ly s t rong peak of an ion with m / e 97 (see Scheme 2 and Table 2).

One of the s t ronges t ions with m / e 125 may a r i s e in the c leavage of bonds in M - 60 (VII, VIII) by type a with the subsequent e ject ion of a molecule of acetone. The ions with m / e 102 and 99 that a re c h a r - ac te r i s t i c fo r compounds (V) and (VI) have a low intensity in the m a s s s p e c t r a of (VII) and {VIH).

E X P E R I M E N T A L M E T H O D

The m a s s s pec t r a were taken on anMKh-1303 ins t rument (direct introduction of the sample) at 200- 210°C for compounds (I-IV) and 130-140°C for (V-VIII) at an ionizing voltage of 40 V. The ecdys te rone and v i t icos terone E used were isolated f r o m Ser ra tu la sogdiana [4]. The p r e p a r a t i o n of the ace ta tes (IH, IV) and the acetonides (V-VIII) is descr ibed in the same paper .

SUMMARY

Fea tures of the f ragmenta t ion of the side chain of the ace ta tes and acetontdes of ecdys te rone and of v i t icos terone E have been studied. It has been shown that the p r e sence of an oxygen-containing function at C2s in these compounds i m pa r t s to the spec t r a ce r t a in distinguishing fea tu res which have analyt ical value.

1. 2. 3. 4.

L I T E R A T U R E C I T E D

M. Koreeda, K. Nakanishi, S. Imai , T. Tsuchiya, and N. Wasada, Mass Spectr . , 1_~7, 669 (1969). M. N. Galbrai th and D. H. S. Horn, Aust. J . Chem., 2__2, 1045 (1969). R. E. Wolff, G. Wolff, and J . A. McCloskey, Tet rahedron, 2_.~2, 3093 (1966). I. L. Zats~y, M. B. Gorovits , and N. K. Abubakirov, Khim. Pr l rodn . Soedin., 175 (1973).

172