87057-53-2

Upstream product

• 493-05-0 isochromane 
• 87057-55-4 Benzoic acid 4-oxo-6-(toluene-4-sulfonyloxymethyl)-4H-pyran-3-yl ester 
• 149296-22-0 Dimethyl <(5-benzyloxy-4-oxo-4H-pyran-2-yl)methyl>-(2-ethenylbenzyl)propanedioate 
• 68642-80-8 5-benzyloxy-2-(toluene-4-sulfonyloxymethyl)-pyran-4-one 
• 149296-20-8 2-(2-Vinyl-benzyl)-malonic acid dimethyl ester 
• 149296-21-9 1-Chloromethyl-2-(2-mesyloxyethyl)benzene 
• 22570-84-9 2-chloromethylstyrene 

Relevant academic research and scientific papers

Cycloadditions of 4-pyrones. An approach to colchicine

The 4-pyrone, [5-acetoxy-4-oxo-4H-pyran-2-yl]carbonyl chloride was coupled with the malonate anion of bis(2,2,2-trichloroethyl) 2-ethenyl-3,4,5-trimethoxybenzylpropanedioate and analogs thereof. These adducts then underwent intramolecular thermal cyclizations (61-100% yield) to form the two fused seven member rings of the carbon skeleton of colchicine. The malonate moiety was deprotected and decarboxylated quantitatively to provide the desired ring system which contained a bridging ether, from C7a to C11 in the C ring, and a ketone at the 7 position. Removal of the bridging ether as H2O would yield the desired tropolone. Our attempts to remove the ether bridge were unsuccessful.

INTRAMOLECULAR CYCLOADDITIONS WITH 2-(ω-ALKENYL)-5-HYDROXY-4-PYRONES

Five 5-hydroxy-4-pyrones, bearing unsaturated side chains at the 2-position, undergo thermal or acid catalyzed cycloaddition to yield bicycloadducts.