Methoxybutenones, reaction with

Evidently, the reaction proceeds via the formation of bis-adduct 289 which undergoes cyclization to dihydropyridine 290. A similar reaction with methoxybutenone, but in the presence of ammonia, which is likely to involve replacement of methoxy group, has been described (80MI2). 

Methoxybut-3-en-2-one with primary amines and acids gives the pyridinium salts, e.g., 222. In this case two molecules of methoxybutenone per one molecule of the amine enter the reaction (62M586). 

The reaction of methoxybutenone with 2-naphthole (FeCF/HCl) involves the addition of the latter to the double bond (adduct 285), cyclocondensation to give hemiacetal 286, and the formation of 2-methyl-5,6-naphtho-(l,2)-pyrylium fer-rochlorate (287) (60MI1). 

Dioxolane derivatives, which are obtained from methoxybutenone and glycols and used as antifungicides, and squalene synthetase inhibitors have been described (94MI1). The reactions of mono- and oligosaccharides with... 

The reaction of methoxybutenone with salicylic aldehyde (20°C, MeOK, toluene, MeOH, 15 h) affords 3-acetyl-2-methoxy-chromo-3-ene (291) in 14% yield (80MI1). 

Preparation of y-pyrone by the reaction of methoxybutenone with formic acid esters (10°C, MeONa, CgHe, 1.5 h) has been reported (73 JPP7229512 80MI2). The intermediate 292 undergoes [3,3]-sigmatropic rearrangement to form methoxydi-hydropyrone 293 which further eliminates methanol, thus transforming to y-pyrone. 

Interestingly, in the reaction of 2-methylindole with methoxybutenone, it is the indole -position, rather than the NH function, that is the reaction site to form 2-methyl-3-acetoxyvinylindole (251), the subsequent intramolecular cyclization of which leads to 2-methoxycarbazole 252 (62TL589). 

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