Catalytic and Regioselective Ring Expansion of Arylcyclobutanones with Trimethylsilyldiazomethane. Ligand-Dependent Entry to β-Ketosilane or Enolsilane Adducts
摘要:
Divergent reactivity is uncovered in the homologation of arylcyclobutanones with trimethylsilyldiazomethane. With Sc(OTf)(3) as catalyst, enolsilanes are obtained with a high preference for methylene migration. By contrast, Sc(hfac)(3) gives beta-ketosilanes with both regio- and diastereocontrol. Each adduct affords the cyclopentanone upon hydrolysis.
2,2-Dimethyl cyclopentanones by acid catalyzed ring expansion of isopropenylcyclobutanols. A short synthesis of (±)-α-cuparenone and (±)-herbertene
作者:Angela M. Bernard、Angelo Frongia、Francesco Secci、Pier P. Piras
DOI:10.1039/b505707h
日期:——
catalyzed ring expansion of isopropenylcyclobutanols; the method allows ready access to the family of sesquiterpenes cuparanes and herbertanes, as demonstrated by the synthesis of (+/-)-alpha-cuparenone and the direct precursor of (+/-)-herbertene.
The First Facile Synthesis of Some 1,2a,3,8b-Tetrahydro-2H-Cyclobuta[c] Chromenes Through Intramolecular Alkylation of an Aromatic Ring by a Cyclobutanone
作者:Angela M. Bernard、Costantino Floris、Angelo Frongia、Pier P. Piras
DOI:10.1055/s-2002-25355
日期:——
Starting from cyclobutanones several new chromenes containing a cyclobutane ring are prepared. Ring fission of these derivatives gives easy access to functionalized 3-isoflavenes.
作者:Melanie A. S. Blackburn、Corin C. Wagen、M. Raul Bodrogean、Pamela M. Tadross、Andrew J. Bendelsmith、Dennis A. Kutateladze、Eric N. Jacobsen
DOI:10.1021/jacs.3c02960
日期:2023.7.19
A catalytic protio-semipinacol ring-expansion reaction has been developed for the highly enantioselective conversion of tertiary vinylic cyclopropyl alcohols into cyclobutanone products bearing α-quaternary stereogenic centers. The method relies on the cocatalytic effect of a chiral dual-hydrogen-bond donor (HBD) with hydrogen chloride. Experimental evidence is provided for a stepwise mechanism where
Synthesis of New Heterocycles through a Cation-Driven Tandem Ring-Enlargement−Annulation Reaction
作者:Angela M. Bernard、Enzo Cadoni、Angelo Frongia、Pier P. Piras、Francesco Secci
DOI:10.1021/ol026199x
日期:2002.7.1
[GRAPHICS]The thionium ion, generated through a cyclopropylcarbinyl-cyclobutyl ring expansion, is, for the first time, intramolecularly intercepted by activated aromatic rings to generate new versatile 2a-methyl-8b-(phenylsulfanyl-1,2a,3,8b-tetrahydro-2H-cyclobuta[c]chromenes.