Cyanoketenes. Cycloadditions of halocyanoketenes to benzaldehydes

Moore, Harold W.; Mercer, Frank W.; KUNERT, D.; Albaugh, Pamela

doi:10.1021/ja00512a065

Cited by 26 publications

(2 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the reactions mentioned so far, a dehydrohalogenation was observed on conducting the reaction starting from 2,3-dibromo-3-phenylpropanenitrile (17g), which yielded (E)-2-bromo-3-phenylacrylonitrile (18f) 24 as the main product (Scheme 8). In this case, 1,2-dimethylindazolium bromide (3) was formed from the NHC 2.…”

Section: Figurementioning

confidence: 89%

N-Heterocyclic Carbenes of Indazole: Ring Enlargement Reactions by α-Halo Ketones and Dehalogenations of Vicinal Dihalides

Schmidt¹,

Snovydovych²,

Gjikaj³

2008

Synthesis

View full text Add to dashboard Cite

On decarboxylation, 1,2-dimethylindazolium-3-carboxylate forms the N-heterocyclic carbene, 1,2-dimethylindazol-3-ylidene, which deprotonates a-halo ketones. The resulting indazolium salt and the corresponding enolate form 1:1 adducts which undergo a ring enlargement to cinnolines. Reaction with 2-bromo-2,3-dihydro-1H-inden-1-one gives a 4-hydroxyspiro[cinnoline-3,2¢-inden]-1¢-one by ring enlargement reaction (X-ray crystal structure analysis). Vicinal dibromides undergo debromination under these conditions to give alkenes, and substrates with 1,2-dibromoethene partial structure give acetylenes. As 3-bromoindazole is found as the second product of this reaction, an E 1cb mechanism, initiated by Br + abstraction by the N-heterocyclic carbene of indazole, is suggested.

show abstract

Section: Figurementioning

confidence: 89%

N-Heterocyclic Carbenes of Indazole: Ring Enlargement Reactions by α-Halo Ketones and Dehalogenations of Vicinal Dihalides

Schmidt¹,

Snovydovych²,

Gjikaj³

2008

Synthesis

View full text Add to dashboard Cite

show abstract

“…Since then, silylketenes have been widely used to prepare β-lactones; particularly, highly stereoselective examples and natural products syntheses were reported. However, the study of the mechanism of this reaction has attracted little experimental attention . Theoretical studies, unlike those devoted to the formation of cyclobutanones, and more recently β-lactams, by [2 + 2] cycloaddition reactions, are also rare …”

Section: Introductionmentioning

confidence: 99%

Formation of β-Lactones through Lewis Acid-Promoted [2 + 2] Cycloaddition Reaction. A Theoretical Study

et al. 1997

View full text Add to dashboard Cite

The formation of β-lactone through Lewis acid-promoted [2 + 2] cycloaddition is studied using semiempirical (AM1/RHF and AM1/CI) and ab initio (HF/6-31G* and MP2/6-31G*) calculations. After a preliminary semiempirical study of the BF3-catalyzed parent reaction through two distinct reaction paths, ab initio and/or semiempirical studies on solvent and Lewis acid (BH3 and BF3) effects concentrate on the mechanism involving the prior formation of the C−C bond. At the HF/6-31G* level of theory the introduction of BF3 induces a reduction of the activation energy from 40.8 to 11.9 kcal/mol, and calculations performed with AM1/COSMO showed that the introduction of a solvent results in the formation of an earlier transition state. The case of BH3 is somehow more complicated since the studied system induces, both at the semiempirical and ab initio levels, a hydride transfer leading to a very stable product.

show abstract

Chlorocyanoketene

Turnbull¹,

Moore²

2001

Encyclopedia of Reagents for Organic Synthesis

View full text Add to dashboard Cite

Cyanoketenes. Cycloadditions of halocyanoketenes to benzaldehydes

Cited by 26 publications

References 0 publications

N-Heterocyclic Carbenes of Indazole: Ring Enlargement Reactions by α-Halo Ketones and Dehalogenations of Vicinal Dihalides

N-Heterocyclic Carbenes of Indazole: Ring Enlargement Reactions by α-Halo Ketones and Dehalogenations of Vicinal Dihalides

Formation of β-Lactones through Lewis Acid-Promoted [2 + 2] Cycloaddition Reaction. A Theoretical Study

Chlorocyanoketene

Contact Info

Product

Resources

About