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Abstract
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A one-pot multi-component pathway is reported to synthesize
novel spiro-(1,8)-naphthyridine derivatives in good to excellent
yields via the condensation reaction of isatin derivatives,
malononitrile dimer and enamine derivatives. In polyethylene
glycol-400 at 80°C, more than 30 novel products of spiro-(1,8)-
naphthyridines were synthesized up to 95% yields with only
water as a by-product. Separation of the products was
performed efficiently and no additional operation was needed
for purification of the products, except that, in some cases,
recrystallization was done. Moreover, some new spiro-dihydropyrimidines
were efficiently synthesized when malononitrile (or
methyl/ethyl-2-cyanomalonate) was employed instead of enamines.
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