scholarly journals New Syntheses and Ring Expansion Reactions of Cyclobutenimines

2010 ◽  
Vol 63 (12) ◽  
pp. 1656 ◽  
Author(s):  
Ernst Schaumann ◽  
Gerrit Oppermann ◽  
Michael Stranberg ◽  
Harold W. Moore
Keyword(s):  
Carbonyl Group ◽  
Ring Expansion ◽  
Synthetic Route ◽  
Tertiary Alcohols ◽  
Ring Enlargement ◽  
Alkyl Derivatives

Two routes are reported for the synthesis of iminocyclobutenones having N-(het)aryl substitution: an addition/substitution sequence starting with cyclobutenediones and an aza-Wittig method. A new synthetic route to N-alkyl derivatives is also presented. This involves O-alkylation of 3-alkylamino-1,2-cyclobutenediones using Meerwein’s reagent and subsequent deprotonation under non-hydrolytic conditions. Lithium organyls were found to add to the remaining carbonyl group. The resulting tertiary alcohols undergo ring enlargement on heating in xylene to give 4-aminophenols, 4-amino-1-naphthols, or cyclopenta-annulated quinolines from 4-vinyl, 4-aryl, and 4-alkynyl derivatives, respectively.

Reaction of dimethoxycarbene with strained cyclic carbonyl compounds

2000 ◽  
Vol 78 (9) ◽  
pp. 1194-1203
Author(s):  
Paul C Venneri ◽  
John Warkentin
Keyword(s):  
Carbonyl Group ◽  
Carbonyl Compounds ◽  
Ring Expansion ◽  
Carbonyl Groups

A cyclopropanone, a cyclopropenone, cyclobutanones, a cyclobutane-1,3-dione, and a cyclobutene-1,2-dione reacted with dimethoxycarbene to afford acetals of the next larger ring by formal insertion of the carbene into a C—C bond α to the carbonyl group. When either of two saturated α-ring carbons could be involved in the process, the ring expansion was selective, affording primarily the product of apparent insertion into the more substituted ring bond. With 2,3-dimethoxycyclobutene-1,2-dione, insertion occurred between the carbonyl groups and with β-propiolactone it occurred at the lactone bond. β-Propiolactam, however, reacted by insertion of the carbene into the N—H bond.Key words: β-propiolactone, cyclobutanone, cyclobutananedione, cyclopropanone, dialkoxycarbene.

scholarly journals Recent Advances in the Catalytic Synthesis of Imidazolidin-2-ones and Benzimidazolidin-2-ones

Catalysts ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 28 ◽  
Author(s):  
Alessandra Casnati ◽  
Elena Motti ◽  
Raffaella Mancuso ◽  
Bartolo Gabriele ◽  
Nicola Della Ca’
Keyword(s):  
Natural Products ◽  
Carbonyl Group ◽  
Ring Expansion ◽  
Catalytic Synthesis ◽  
Chiral Auxiliaries ◽  
Aziridine Ring ◽  
Urea Derivatives ◽  
Structural Motifs ◽  
Recent Advances ◽  
Direct Incorporation

2-Imidazolidinone and its analogues are omnipresent structural motifs of pharmaceuticals, natural products, chiral auxiliaries, and intermediates in organic syntheses. Over the years, continuous efforts have been addressed to the development of sustainable and more efficient protocols for the synthesis of these heterocycles. This review gives a summary of the catalytic strategies to access imidazolidin-2-ones and benzimidazolidin-2-ones that have appeared in the literature from 2010 to 2018. Particularly important contributions beyond the timespan will be mentioned. The review is organized in four main chapters that identify the most common approaches to imidazolidin-2-one derivatives: (1) the direct incorporation of the carbonyl group into 1,2-diamines, (2) the diamination of olefins, (3) the intramolecular hydroamination of linear urea derivatives and (4) aziridine ring expansion. Methods not included in this classification will be addressed in the miscellaneous section.

Oxidative Dearomatization and Sigmatropic 1,3-Acyl Shift in Excited State: Aromatics to Embellished cis-Hydrindanes

Synthesis ◽  
2019 ◽  
Vol 51 (07) ◽  
pp. 1633-1642
Author(s):  
Vishwakarma Singh ◽  
Raghaba Sahu
Keyword(s):  
Excited State ◽  
Ring Expansion ◽  
Synthetic Route ◽  
Oxidative Dearomatization ◽  
Key Features

A stereoselective synthetic route to embellished cis-hydrindanes from simple aromatic precursors is described. Oxidative dearomatization, ring expansion, and photochemical 1,3-acyl shift are the key features of our approach. Oxidative dearomatization of o-(hydroxymethyl)phenols followed by π4s + π2s cycloaddition furnishes bicyclo[2.2.2]octanes with contiguous keto epoxide groups, which upon ring expansion lead to bicyclo[3.2.2]nonanes endowed with a β,γ-enone chromophore. Unbridging of bicyclo[3.2.2]nonanes upon singlet excitation furnishes embellished cis-hydrindanes.

Sur l'aptitude à l'extension du noyau pipéridique en fonction de la substitution de l'atome d'azote: réaction du diazométhane avec quelques pipéridones-4 et désamination nitreuse des aminométhyl-alcools correspondants

1971 ◽  
Vol 49 (19) ◽  
pp. 3075-3085 ◽  
Author(s):  
H. Favre ◽  
Z. Hamlet ◽  
R. Lanthier ◽  
M. Ménard
Keyword(s):  
Nitrogen Atom ◽  
Carbonyl Group ◽  
Nitrous Acid ◽  
Ring Expansion ◽  
Nucleophilic Attack ◽  
Electronic Effects ◽  
Field Effects ◽  
Benzoyl Group ◽  
La Substitution

Aptitude to ring expansion in the piperidine series, measured by the ratio of ring expanded ketone to epoxide, varies considerably according to the nitrogen atom substituent. This ratio is essentially the same in the case of the reaction of diazomethane on 4-piperidones and the nitrous acid deamination of the corresponding aminoalcohols. The values of the ratio are 0.01–0.1 for a phenylsulfonyl group, of the order 0.3–0.6 for a benzoyl group and slightly greater than 1 for a benzyl group. Electronic effects (inductive and field effects) are the cause of these differences. Parallels between the two reactions indicate that nucleophilic attack of diazomethane on the carbonyl group can lead to the ring expanded ketone and the epoxide.

A novel synthetic route to 2-alkylpropane-1,3-sultones and its application to the synthesis of 2-alkyl derivatives of tramiprosate

2007 ◽  
Vol 48 (49) ◽  
pp. 8587-8589 ◽  
Author(s):  
Benoit Bachand ◽  
Mohamed Atfani ◽  
Bita Samim ◽  
Sophie Lévesque ◽  
Daniel Simard ◽  
...  
Keyword(s):  
Synthetic Route ◽  
Alkyl Derivatives ◽  
Derivatives Of
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