Synthesis by construction of the second heterocyclic ring onto an existing heterocycle

1 Synthesis by construction of the second heterocyclic ring onto an existing heterocycle 10.01.9.1.1 Benzoderivatives 

The compound 352 was prepared as a new type of a core for ferroelectric liquid crystals 2000CCC1939 . 

Treatment of 2,2 -dibromodiphenylacetylene 353 with / /t-butyllithium followed by tellurium insertion resulted in ring closure to afford [l]benzotelluro[3,2-3][l]benzotellurophene 354 (Equation 6). Similarly, [l]benzoseleno[3,2-/ ]-[IJbenzoselenophene 355 and [l]benzothieno[3,2-3][l]benzothiophene 356 were also obtained 1998JHC725 . 

A new stabilized phosphorus ylide 357 designed to undergo thermal tandem cyclization has been prepared. Upon flash vacuum pyrolysis at 850 °C, loss of PhsPO and Me radical results in tandem cyclization to give [l]ben-zothieno[3,2- ][l]benzothiophene 356 (Equation 7) 1998J(P1)3937 . 

General procedures for the synthesis of 10f/-[l]benzothieno[3,2- ]indoles 359a-c 2003T3737 and 2,4-dimethylpyrrolo[3,2-, ]indole 360 1997J(P1)2843 using palladium-catalyzed intramolecular cyclization of the appropriate o-bromodiarylamines and palladium-catalyzed arylation of a cyano group, respectively, were described. 

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Synthesis by Construction of the Second Heterocyclic Ring onto an Existing Heterocycle... 

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