Ketene, chlorocarbonyl-phenyl

Bielectrophiles have found appreciable applications in the synthesis of ring-fused systems, especially those involving [5,6] fused systems. The following serve to illustrate these applications. Reaction of pyrazole with (chlorocarbonyl)phenyl ketene (214) (Type 1, Scheme 6) readily formed the zwitterionic pyrazolo[l,2-a]pyrazole derivative (215) (80JA3971). With l-methylimidazole-2-thione (216), anhydro-2-hydroxy-8-methyl-4-oxo-3-phenyl-4//-imidazo[2,l-6][l,3]thiazinium hydroxide (217) was obtained (80JOC2474). 

Diketones and a-(chlorocarbonyl)phenyl ketene react to provide the intermediate ketene 645, which can cyclize to afford 2/7-pyran-2-ones in high yield (Scheme 150) <2004T5931>. Similarly, silyl enol ethers react with ot-(chlorocarbonyl)mesitylketene to afford 2//-pyran-2-ones (Equation 260) <2001T4133>. 

Reaction of 1,2-allenyl esters and 1, catalyzed by potassium carbonate, gave 456a through a tandem nucleophilic addition-lactoniza-tion process (06S2731). The (chlorocarbonyl)phenyl ketene was condensed with 1 to give 456 (R = Ph) (04T5931). 

The addition of (chlorocarbonyl)phenyl ketene 126 to 3-alkyl-1-phenyl-2-pyrazolin-5-ones 141 resulted in 4-hydroxy-3-alkyl-l,... 

C14H20CINO2) see Bietamiverine phenyl(chlorocarbonyl)ketene (QHjCIOj 17118-70-6) see Carindacillin phenyl chloroformate... 

Phenyl(chlorocarbonyl)ketene 170 reacts with N-phenylacetyknorpho-line forming 4-hydroxy-6-morpholino-3,5-diphenylpyran-2-one in a process interpreted as involving initial esterification of the acylketene with the enol of the amide followed by generation of a second acyl ketene 171 and further cyclization to 172 (Eqn (4.109)). Ketene 170 also reacts similarly with 1,3-diketones and heterocyclic 3-hydroxy-2-ene-l-ones forming polycyclic lactones. 

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