A new method for the synthesis of azaheterocycles based on cascade reactions of nitrogen- and phosphorus-containing ylides with methyl diazoacetate

Reduction of the double bonds in heptamethyl cycloheptatriene-1,2,3,4,5,6,7-heptacarboxylate

“…6- 8 We assumed that cycloheptatrieneheptacarboxylate 1 Table 1. Bond lengths (d) between the cyclic carbon atoms in compounds 2, 3, and 5…”

Synthesis of tetrasubstituted pyridazines via cascade reactions of diazocarbonyl compounds with pyridinium ylides

“…With diazoacetone, azine 9a contains different substituents at reactive carbonyl groups, which leads to a mixture of pyridazines 11 and 12 in the ratio ~2.6 : 1. The isomers were assigned from the 1 H and 13 C NMR chemical shifts of the signals for the methyl groups: δ H 2.1-2.2 and δ C 15-16 for MeC (5) and δ H 2.6-2.9 and δ C 25-27 for MeCOC (3). It should also be noted that each of the pyridazines 10-12, like pyridazines 3 and 4, exists in solution in the ketone and enol forms: their 1 H and 13 C NMR spectra show charac teristic signals for the methylene and olefinic protons (see Table 1).…”

“…1,2 Such reactions are of cascade character and involve sequential interactions of two molecules of phosphorus ylide (or three molecules of nitrogen ylide) with a molecule of diazo ester with simultaneous elimination of the ylide forming molecule. 3 For pyridinium ylides 1 containing a carboxyl or carbonyl group, these processes usually differ in the final step, namely, heterocyclization (Scheme 1). In the case of an azine containing four ester groups, cyclization leads, through the corresponding ene hydrazone, 1 to tetrahydropyridazinetetracarboxylate 2; for an azine containing a conjugated carbonyl group, cyclization gives tetrasubstituted pyridazine 3 via aldol condensation.…”

“…In the case of an azine containing four ester groups, cyclization leads, through the corresponding ene hydrazone, 1 to tetrahydropyridazinetetracarboxylate 2; for an azine containing a conjugated carbonyl group, cyclization gives tetrasubstituted pyridazine 3 via aldol condensation. 3 In both cases, the overall "one pot" pro cess results in the formation of one C-N bond and three new carbon-carbon bonds.…”

Acetylmethylenetriphenylphosphorane

“…Acetylmethylenetriphenylphosphorane also reacts with methyldiazoacetate to produce a substituted pyrazole product (eq 30). 35 Two molecules of the ylide are used in this process to form the product and a suggested reaction pathway is shown below. …”