92919-44-3

Upstream product

• 79962-35-9 2-Dimethylamino-3-methyl-2,4,6-triphenyl-2H-pyran 
• 75-36-5 acetyl chloride 
• 79888-87-2 2-methoxy-3-methyl-2,4,6-triphenyl-2H-pyrane 
• 98-88-4 benzoyl chloride 

Relevant academic research and scientific papers

Pyrylium Compounds. XXIII. 2-Dialkylamino-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts

Tetra- and pentasubstituted pyrylium salts of type 6 react with secondary alkyl amines to give stable crystalline 2-dialkylamino-2H-pyrans 7.In the case of tetrasubsituted pyrylium salts 6, R' = Me, R'' = H the reaction occurs regioselectively leading to 2H-pyrans with Me at C-3 of the heterocyclic ring.The structure of the reaction products was established by n.m.r., i.r., u.v. and mass spectroscopic methods.Electrophilic agents like protons, carboxylic acid chlorides or methyl iodide regenerate the original pyrylium cations from 7.In refluxing methanol 7a is converted into the 2-methoxy-2H-pyran derivative 8, whereas in aqueous acetone the pseudobase 9 and with ammonia the pyridine 10 are formed.Reaction of 7a with nitromethane or ethyl cyanoacetate provides the benzene derivatives 11 and 12, respectively.

Pyrylium Compounds. XVIII. 2-Alkoxy-2H-pyrans from Tetra- and Pentasubstituted Pyrylium Salts

Alkali alkoxides add regioselectively to 2,3,4,6-tetrasubstituted pyrylium salts 7 (R'=H), affording high yields of colourless crystalline 2-alkoxy-2H-pyrans 9.The latter are also formed simply on refluxing 7 in the corresponding alcohol with triethylamine as proton acceptor. 3,5-Dialkylsubstitued 2,4,6-trialkylpyrylium salts react analogously.The 2H-pyran structure of the adducts obtained follows from their n.m.r., i.r., u.v. and mass spectra as well as from their reaction with tetracyanoethylene to cycloadducts of type 10.Acids regenerate from 9 the original pyrylium cations, whereas reaction of 9 with nitromethane or ethyl cyanoacetate provides benzene derivatives. - The novel starting pyrylium salts 7b-o are characterized by u.v./vis data and by transformation into the corresponding pyridine derivatives.