Palladium-Catalyzed Cascade Approach to 12-(Aryl)indolo[1,2- c ]quin­azolin-6(5 H )-ones

A straightforward one-pot approach to the synthesis of challenging 12-arylindolo[1,2-c]quinazolin-6(5H)-ones is described. Starting from readily available o-(o-aminophenylethynyl)trifluoroacetanilides, palladium-catalyzed aminoarylation of the triple bond with ArI, ArBr, and ArN2 +BF4 – is followed by cyclization of the resulting N-trifluoro­acetyl-2-(o-aminophenyl)-3-aryl indole. This sequential reaction provides the title compounds by means of a rare elimination of trifluoromethane

The palladium-catalyzed hydroarylation and hydrovinylation of carbon-carbon multiple bonds: new perspectives in organic synthesis

A t t i v e , U n i v e r s i t l "La Sapienza", P.le A. Moro 5 , 00185 Roma ( I t a l y ) GENERAL CONSIDERATIONS It i s w e l l known t h a t o-aryl and o -v i n y l p a l l a d i u m complexes can r e a c t w i t h carbon-carbon double bonds t o produce v i n y l i c s u b s t i t u t i o n products This r e a c t i o n , t h e Heck's r e a c t i o n , has been t h e s u b j e c t o f several mechanistic and s y n t h e t i c studies and has a wide f i e l d o f a p p l i c a t i o n i n organic synthesis.1 o-Alkylpalladium complexes ( l ) , however, under s u i t a b l e r e a c t i o n conditions, are able t o undergo a carbon-pal ladium bond f i s s i o n s u b s t i t u t i n g t h e carbon-hydrogen bond f o r t h e carbon-palladium bond (pathway -b ) . The n e t r e s u l t i s t h e formation o f t h e a d d i t i o n product ( 4 ) . Oepending on t h e nature o f t h e added carbon u n i t , h y d r o a r y l a t i o n (R = a r y l ) and A r e l a t e d a d d i t i o n r e a c t i o n can occur by r e a c t i n g o -a r y l and o-vinylpalladium h y d r o v i n y l a t i o n (R = a l k e n y l ) r e a c t i o n s can be performed. intermediates w i t h a c e t i l e n i c systems. R = a r y l , alkenyl The aim o f t h e present review i s t o r e p o r t an account on these palladiuro-catalyzed a d d i t i o n r e a c t i o n s w i t h o l e f i n i c and a c e t i l e n i c systems. O l e f i n s c o n t a i n i n g p a r t i c u l a r s t r u c t u r a l features, however, can produce a d d i t i o n products ( 4 ) . For example c y c l i c , s t r a i n e d o l e f i n s , l i k e norbornenes, are almost i d e a l substrates f o r such a r e a c t i o n . I n f a c t , o-alkylpalladium intermediates (51, derived from t h e a d d i t i o n o f RPdX species t o t h e carbon-carbon double bond, are unable t o undergo r o t a t i o n t o reach t h e conformation r e q u i r e d f o r t h e syn-&elimination o f HPdX and can w a i t f o r r e a c t i n g w i t h t h e hydrogen donor. Some b i c y c l i c o l e f i n i c systems have been r e p o r t e d t o r e a c t w i t h a r y l and v i n y l h a l i d e s i n t h e presence o f P~( O A C )~( P P~~)~, f o r m i c a c i d as t h e hydrogen donor, and n-Bu3N as t h e base2 o r P~( O A C )~, n-Bu4NC1, and HCOOK (HCOONa, HCOOLi and HCOOCs were a1 so t e s t e d ) 3 t o g i v e t h e corresponding hydroaryl ated and hydrovi n y l ated d e r i v a t i v e s (7) u s u a l l y i n good y i e l d . a) Olefins Usually mono-and d i s u b s t i t u t e d o l e f i n i c systems do n o t undergo h y d r o a r y l a t i o n and h y d r o v i n y l a t i o n r e a c t i o n s . The syn-8-elimination o f HPdX i s by f a r t h e 71

Heterocycles via cyclization of alkynes promoted by organopalladium complexes

Two general classes of reactions leading to heterocycles are reviewed: the sequential hydroarylation(hydrovinylation)/cyclization of alkynes containing proximate nucleophilic and electrophilic centers, a process which combines the palladium-catalyzed cis addition of an aryl or vinyl unit and a hydrogen atom to the carbon–carbon triple bond with the formation of a new bond between the nucleophile and the electrophile; the palladium-catalyzed cyclization of alkynes containing proximate nucleophiles with organopalladium complexes, which is based on a trans heteropalladation/reductive elimination tandem reaction