Electron impact ionization mass spectra of some substituted dipyrido[1,2-a:4,3-d] pyrimidinones

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DEPARTMENT OF CHEMISTRY, UNIVERSITY OF JYVÄSKYLÄ RESEARCH REPORT No. 39

VI NATIONAL SYMPOSIUM ON MASS SPECTROMETRY

J Y V Ä S K Y L Ä 1 3 . - 1 5 . 5 . 1 9 9 2

A B S T R A C T S Edited

by Anja Veijanen

Jyväskyiä. Finland 1992 ISBN 951-680-751-8

ISSN 0375-346X

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E L E C T R O N I M P A C T IONIZATION MASS S P E C T R A O F S O M E S U B S T I - T U T E D D I P Y R I D O [ 1 , 2 - a : 4 , 3 - d ] P Y R I M I D I N O N E S

K a l e v i P i h l a j a and Esa M a k i * *

D e p a r t m e n t o f C h e m i s t r y , U n i v e r s i t y of T u r k u , S F - 2 0 5 0 0 T u r k u , F i n l a n d

I m r e H u b e r , F e r e n c Fülöp and G á b o r B e m á t h

I n s t i t u t e o f Pharmaceutical C h e m i s t r y , A l b e r t S z e n t - G y ö r g y i M e d i c a l U n i v e r s i t y , H-6720 S z e g e d , H u n g a r y

T h e a i m of t h i s study is to report t h e e l e c t r o n i m p a c t i o n i z a t i o n m a s s s p e c t r a of 20 d i p v r i d o [ 1 , 2 - a : 4 , 3 - d ] - p y r i m i d i n - l l - o n e s , t h e structures of w h i c h a r e r e p r e - s e n t e d i n T a b l e 1 . T h e degree of a r o m a t i c i t y of t h e t r i c y c l e v a r i e s from compound to c o m p o u n d .

1 2 3

T h e s u b s t i t u e n t s R , R and R of t h e d i p y r i d o - [1, 2 - a : 4 , 3 - d ] p y r i m i d i n - l l - o n e s did n o t h a v e a n y d e c i s i - v e e f f e c t o n t h e i r fragmentation. Instead t h e c o n j u g a - t i o n of t h e d o u b l e b o n d s and the d e g r e e o f a r o m a t i z a - t i o n d i r e c t e d the m o l e c u l a r c l e a v a g e s v e r y s t r o n g l y . So t h e s e c o m p o u n d s c a n be divided into four g r o u p s (1 - 1 3 , 14 - 1 5 , 16 and 17 - 20), i n s i d e w h i c h t h e r e w e r e m a n y s i m i l a r i t i e s in f r a g m e n t a t i o n s .

T h e m o l e c u l a r ions of a l l the c o m p o u n d s s t u d i e d w e r e q u i t e s t a b l e . T h e ions [ M - P h C ^ ]¹" from c o m p o u n d s 1 - 6 a n d [M-H]¹" f r o m 7 - 1 0 fragmented s i m i l a r l y . C h a r a c t e - r i s t i c a l l y t h e y lost 23 m . u . Ey a c c u r a t e m a s s m e a s u r e - m e n t s i t w a s proved that the r e s u l t i n g p e a k w a s a d o u b l e t w h e r e the m a i n component r e s u l t e d from t h e l o s s o f H-CN" a n d t h e m i n o r component from t h e l o s s of C O . T h e f o r m e r c o m p o n e n t l o s t further a n o t h e r 28 m . u . T h i s t i m e t h e m a i n route corres-ponced to a l o s s o f C O .

T h e f r a g m e n t a t i o n of compounds 14 and 15 w a s f a i r l y s c a r c e and i t was d o m i n a t e d by loss of s i m p l e h y d r o c a r - b o n f r a g m e n t s . In the spectrum of c o m p o u n d 16 t h e o n l y s i g n i f i c a n t p e a k s in addition to t h a t of MT" c o r r e s p o n - d e d t o t h e i o n s [ M - H C N ]T * and [ M - H C N - C O ]T' . S p l i t t i n g o f h y d r o c a r b o n and CO fragments c o u l d b e o b s e r v e d a l s o i n c o m p o u n d s 17 - 2 0 .

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Table 1. The structures of the studied compounds.

V

C o m p o u n d R1 R2 R3

1 P h C H2 H H

2 P h C H 2 6 - M e H

3 P h C H2 7 - M e H

4 P h C H2 8 - M e H

5 P h C H2 9 - M e . H

6 P h C H2 7 - M e 9 - M e

7 H H H

8 H H 6 - M e

9 H H 8 - M e

10 H H 9 - M e

1 1 P h C H2 6 - O H H

12 P h C O 9 - M e H

13 H C C H2C H2C H2 9 - M e H

14

1 5

R - H R =» Me

o ¡ e

c.h,

16

17 13 19 20

R - H , n =1 H , R2 - M e , n = 1 P h C H2, R2 - H , n R2 - H , n - 2