Showing papers by "Curt Wentrup published in 1976"
91 citations
49 citations
TL;DR: The flash pyrolysis of 4-arylmethylidene-3-methyl-5(4H)-isoxazolones (3) yields carbon dioxide, acetonitrile, and phenylacetylenes substituted by alkoxy, chloro, dimethylamino, and hydroxy groups, in yields of 45-95% as mentioned in this paper.
Abstract: Flash pyrolysis of 4-benzylidene-2-phenyl-5(4H)-oxazolone (1) yields carbonmonoxide, benzene, biphenyl, diphenylacetonitrile, and 2,3-diphenylsuccinonitrile; N-benzoylphenylketenimine is implicated as the primary intermediate. The flash pyrolysis of 4-arylmethylidene-3-methyl-5(4H)-isoxazolones (3) yields carbon dioxide, acetonitrile, and phenylacetylenes substituted by alkoxy, chloro, dimethylamino, and hydroxy groups, in yields of 45–95%. Arylmethylidenecarbenes are implicated as intermediates.
33 citations
32 citations
TL;DR: In this paper, the reaction of 4-chloro-2-phenylquinazoline with K15NN2 has been studied by 15N-NMR spectroscopy.
Abstract: The reaction of 4-chloro-2-phenylquinazoline with K15NN2 has been studied by 15N-NMR. spectroscopy. 15N-chemical shifts in 5-phenyl-1 (3)-[15N]-tetrazolo[1,5-c]quinazoline and -Nα(Nγ)-[15N]-4-azido-2-phenylquinazoline are reported. The characteristic IR. absorption frequencies of the tetrazole group have been determined in a series of annelated 15N-labelled compounds. From these studies and the chemistry of the labelled tetrazoles, it is concluded that all haloazines examined react with KN3 by the direct nucleophilic substitution mechanism. An addition of nucleophile-ring opening-ring closure (ANRORC) mechanism was not observed. The synthesis of several 15N-labelled tetrazoloazines is described.
19 citations
TL;DR: In this article, it was shown that carbene-carbene rearrangements are favored by a nucleophilic interaction between the filled singlet carbene sp2 (σ) orbital and the lowest unoccupied molecular orbital (LUMO) of the aromatic ring.
Abstract: Flash pyrolysis of 4-biphenylyl-4-pyridyldiazomethane (4 gave 7-phenyl-2-azafluorene)5, which was also synthesized from 3-mesitoylpyridine in four steps. 4-Biphenylyl-4-pyridyl-[13C]-diazomethane (9) was prepared from isonicotinic [13C]-acid chloride in three steps. Flash pyrolysis of 9 established that 4a- and 4b-[13C]-7-phenyl-2-azafluorenes are formed in a carbene-carbene rearrangement in which ring expansion of the biphenyl part dominates over that of the pyridine ring. These results support the postulate that carbene-carbene rearrangements are favoured by a nucleophilic interaction between the filled singlet carbene sp2 (σ) orbital and the lowest unoccupied molecular orbital (LUMO) of the aromatic ring.
17 citations
TL;DR: In this paper, it was shown that only the isocyanoamines not the isomeric nitrile imines are intermediates in the formation of indazoles.
Abstract: Flash pyrolysis of the 4-arylhydrazono-3-methyl-isoxazol-5-one (1) yields carbon dioxide, acetonitrile, and isocyanoarylamines 2 which under the reaction conditions rearrange to either arylcyanamides 3 or indazoles 4. It is shown by deuterium labelling that only the isocyanoamines not the isomeric nitrile imines are intermediates in the formation of indazoles.
16 citations
TL;DR: A simplified high-yield preparation of end-labelled potassium azide from K15NO3 is described, which gives ring-labelling 1-cyanoimidazoles in 80–100% yields.
Abstract: A simplified high-yield preparation of end-labelled potassium azide from K15NO3 is described. Treatment of 4-chloropyrimidines with K15NN2 and subsequent gas-phase pyrolysis gives ring-labelled 1-cyanoimidazoles in 80–100% yields. The cyano-groups in the latter are easily removed by hydrolysis.
8 citations
TL;DR: In this article, it was shown that carbene-carbene rearrangements are favored by a nucleophilic interaction between the filled singlet carbene sp2 (σ) orbital and the lowest unoccupied molecular orbital (LUMO) of the aromatic ring.
Abstract: Flash pyrolysis of 4-biphenylyl-4-pyridyldiazomethane (4 gave 7-phenyl-2-azafluorene)5, which was also synthesized from 3-mesitoylpyridine in four steps. 4-Biphenylyl-4-pyridyl-[13C]-diazomethane (9) was prepared from isonicotinic [13C]-acid chloride in three steps. Flash pyrolysis of 9 established that 4a- and 4b-[13C]-7-phenyl-2-azafluorenes are formed in a carbene-carbene rearrangement in which ring expansion of the biphenyl part dominates over that of the pyridine ring. These results support the postulate that carbene-carbene rearrangements are favoured by a nucleophilic interaction between the filled singlet carbene sp2 (σ) orbital and the lowest unoccupied molecular orbital (LUMO) of the aromatic ring.