1987
DOI: 10.1021/jo00387a031
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Reactions of aldehydes with hydrazine hydrochlorides in the presence of dipolarophiles: intra- and intermolecular [3+ + 2] cycloadditions

Abstract: The reaction of 2 molar equiv of several 2-(alkenyloxy)-l-naphthaldehydes (2) with hydrazine dihydrochloride (3) and subsequent treatment of the mixture with triethylamine lead to intramolecular [3+ + 2] criss-cross cycloadducts 5, 2:1 molar products of 2 and 3, in high yields. On the other hand, naphtho [l',2':5,6]pyrano-[4,3-c]pyrazoles 11 and 12, equimolar products of 2 and 3, were obtained by a similar series of reactions using a large excess of 3. Many pyrazolium chlorides (25), 2,2-dimethyl derivatives o… Show more

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Cited by 57 publications
(15 citation statements)
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“…[3,7,8] The second group may be considered as an intramolecular cycloaddition. Depending upon the regioselectivity of the reaction, we can observe formation of laterally [9,10] or centrally [11,12] fused heterocyclic compounds. The third group is a combination of the first and the second approaches: a combined intra-intermolecular cycloaddition.…”
Section: Introductionmentioning
confidence: 99%
“…[3,7,8] The second group may be considered as an intramolecular cycloaddition. Depending upon the regioselectivity of the reaction, we can observe formation of laterally [9,10] or centrally [11,12] fused heterocyclic compounds. The third group is a combination of the first and the second approaches: a combined intra-intermolecular cycloaddition.…”
Section: Introductionmentioning
confidence: 99%
“…Reaction of monosubstituted hydrazones 10b-l with BF 3 ·OEt 2 results in ionic intermediates 22b-l, which can undergo tautomerization to give the quasi-azomethine imine 1,3-dipolar intermediates 23b-l. [15] Coordination to the Lewis acid of phenylhydrazones containing an electron-donating group (CH 3 or OMe) on the aromatic ring, as in 10d or 10e, is presumed to be somewhat more favorable than that of phenylhydrazones with an electronwithdrawing group (NO 2 , CN, CF 3 ) in 10f-i or of acetylhydrazone 10b. [16] Nevertheless, complexation and the following N,NЈ-proton shift are assumed to occur under the given reaction conditions to afford intermediates 23b-l.…”
Section: Resultsmentioning
confidence: 99%
“…the simple hydrazine catalyst 10, the carbonyl-olefin metathesis was demonstrated for a range of aryl and heterocyclic aldehydes (11) in generally good to excellent yields (Scheme 5). An inverse correlation between the electron-rich character of 11 and the yields of the isolated products was reported, and was presumed to be due to the sensitivity of the electronrich products to decomposition.…”
Section: Angewandte Highlightsmentioning
confidence: 99%