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Addition of Chlorosulphonyl Isocyanate to Tetrasubstituted Cyclopentadienes: A Facile Route for the Synthesis of Azepines

1984; Elsevier BV; Volume: 22; Issue: 12 Linguagem: Inglês

10.3987/r-1984-12-2751

1881-0942

Krishna Narasimhan, Perumal Raja Kumar, T. Mohana Selvi,

Chemical synthesis and alkaloids

The p l a c t a m s , obtained by the c y c l o a d d i t i o n of chlorosulphonyl isocyanate t o the dienes 1, 2 give the aeepinones 5, 2 through tb sulphonate e s t e r e 9, g.The sulphonate e s t e r 6 obtained from 4, when t r e a t e d w i t h sodium h y d d d e g i v e s the dihydmnzepine 5. 1 2 Chloroeulphonyl isocyallate (CSI) is v e r y reactive towards a v a r i e t y of o l e f i n s .TetraphenylcyclopntadietE I and 7,9-di~henyl-8H-cyclopenta(a)-acenaphthylene could r e a c t r d t h CSI by many pathways.W e wish to r e p o r t a f a c i l e m u t e f o r t h e s y n t h e s i s of azepines thmugh the sulphonate e a t e r e 4, 4 ~.CSI r a p i d l y r e a c t e d with tetraphenylcyclopentadiene i n anhydrous e t h e r to give t h e sulphonyl c h l o r i d e 2 , e x h i b i t e d i n i t s i r spectrum *lactam carbonyl a t 1755 cm-'.The 'Humr spectmm of 2 showed t h e presence of a l l y l i c p m t o n e a s a s i n g l e t a t 6 4.24 i n a d d i t i o n t o a m u l t i p l e t a t 66.9-7.2 f o r t h e aromatic pmtona.The sulphonyl c h l o r i d e 2 r e a c t e d w i t h w a t e r t o give the sulphonic a c i d 2 a s a yellow s t a b l e s o l i d .The i r Bpectmrn of 2 e x h i b i t e d tb lactam carbonyl a t 1725 cm-I and tb s h F f t i n tb lactam JC=O a u l d l s due t o intramolecular hydmgen bonding between lactam >C=O and SO H gmup.The 'Humr spectrum of 1 displayed sharp 3 s i n g l e t a t 6 4 .5 3 f o r tka a l l y l i c protons. a broad a i n g l e t a t 6 5.65-5.75.which disappeared on adding D2B and t h e ammatic protons appeared a s a m u l t i p l e t a t 66.8-7.2.2 r e g e m r a t e d 1 when t r e a t e d w i t h e w a n o l i c KOH.The equivalence of the a l l y l i c protons i n ' Hnmr and the h l g h e r JC=O i n ir l e n d support f o r t h e (2+2) mode of a d d i t i o n .Addition of CSI to indene has keen r e p o r t e d t o g i v e similar 3 p-lactam .