The reaction of methyl diazoacetate with 4,4-dimethyl-2-pentyn-1-al and related compounds

1,3-dipolar cycloaddition of trimethylsilyl azide to propynals and dimerization of 1H-1,2,3-triazole-5-carbaldehydes to tricyclic bis-hemiaminals

“…The results of our spectral studies indicate that the dimerization of 5-formyl-1,2,3-triazoles to tricyclic hemiaminals is favored by elevated temperature and increased polarity of the medium. These data contradict those reported by us previously for dimerization of pyrazolecarbaldehydes [1,2], according to which the…”

“…Using a wide series of substituted propynals we previously showed [1][2][3] that these compounds act as ambident electrophiles toward methyl diazoacetate. Depending on the propynal structure, the reactions with methyl diazoacetate follow 1,3-dipolar cycloaddition pattern with formation of isomeric pyrazoles and products of dimerization of 5-formylpyrazoles to tricyclic bis-hemiaminals or/and aldol-like condensation to give α-diazo-β-hydroxyalkynes (in the absence of initiating species).…”

“…Taking into account that, unlike many NH-azolecarbaldehydes which exist as dimeric bis-hemiaminals in the absence of a solvent [1][2][3][4], compounds IV and V in crystal retain their formyltriazole structure, we tried to find conditions promoting their dimerization to heterocyclic bis-hemiaminas. For this purpose, we examined the effects of the polarity of the medium and temperature by 1 H NMR and IR spectroscopy.…”

“…We previously showed [1] that treatment of dimethyl 4,9-dihydroxy-3,8-bis(triethylgermyl)-4H,9Hdipyrazolo[1,5-a:1',5'-d]pyrazine-2,7-dicarboxylate with hexamethyldisilazane (IX) gives the corresponding bis(trimethylsilyl) ether. Assuming that silylation of the dimer should promote displacement of the monomer-dimer equilibrium toward the latter, formyltriazole IV was heated in boiling hexamethyldisilazane (IX) for 4 h. The residue obtained by removal of excess reagent IX showed in the IR spectrum (mineral oil) an absorption band at 1050 cm -1 (Si-O-C) [11], while no carbonyl or NH absorption band was present.…”

Chemistry of heterocyclic compounds at the A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, over 50 years (Review)

“…Methods were developed for the synthesis of polyfunctionalized pyrazoles by the reactions of various acetylene compounds with diazo compounds [264][265][266][267] Low-temperature reactions of isothiocyanates with lithium and potassium amides were discovered and studied systematically, and a fundamentally new strategy for the one-pot assembly of pyrroles [99,102,[171][172][173], thiazoles [99,[273][274][275][276][277][278], and imidazoles [277][278][279][280][281] was developed from them. SR 1 R 1 S By using a mixture of heterocumulenes it is possible to achieve the controlled cascade assembly of polyfunctionalized thiazoles [99,277].…”