Organocatalytic regiospecific synthesis of 1H-indene-2-carbaldehyde derivatives: suppression of cycloolefin isomerisation by employing sterically demanding catalysts
作者:Hui Mao、Dong Wan Kim、Hun Yi Shin、Choong Eui Song、Jung Woon Yang
DOI:10.1039/c6ob01918h
日期:——
The regiospecific synthesis of 1H-indene-2-carbaldehyde derivatives was achieved through transition-metal-free, reductive cyclisation of ortho-formyl trans-cinnamaldehydes with Hantzsch ester in the presence of an aminocatalyst. In particular, cycloolefin isomerisation of the resulting products could be inhibited efficiently by the introduction of a stericallydemanding stereo-defined aminocatalyst
Regiodivergent Cyclobutanone Cleavage: Switching Selectivity with Different Lewis Acids
作者:Laetitia Souillart、Nicolai Cramer
DOI:10.1002/chem.201406135
日期:2015.1.26
diverse building blocks. Herein, Lewisacidcatalyzed rearrangement reactions are presented that provide selective access to two structurally distinct polycyclic scaffolds, that is, indenylacetic acid derivatives and benzoxabicyclo[3.2.1]octan‐3‐ones. The choice of the Lewisacid fully controls the reactionpathway and the regioselectivity of the cyclobutanone CCbondcleavage site.
Gold-Catalyzed Stereoselective Synthesis of 9-Oxabicyclo[3.3.1]nona-4,7-dienes from Diverse 1-Oxo-4-oxy-5-ynes: A Viable Formal [4 + 2] Cycloaddition on an <i>s</i>-<i>trans</i>-Heterodiene Framework
作者:Tse-Min Teng、Arindam Das、Deepak B. Huple、Rai-Shung Liu
DOI:10.1021/ja106493h
日期:2010.9.15
We report a highly stereoselective Au-catalyzed synthesis of 9-oxabicyclo[3.3.1]nona-4,7-dienes from diverse 1-oxo-4-oxy-5-ynes. Formation of these highly strained anti-Bredt oxacycles implies the workability of an unprecedented 1,4-dipole of s-trans-methylene(vinyl)oxonium. This work reveals the feasibility of a formal [4 + 2] cycloaddition on an s-trans-heterodiene framework.
Highly Enantioselective Rhodium(I)-Catalyzed Carbonyl Carboacylations Initiated by CC Bond Activation
作者:Laetitia Souillart、Nicolai Cramer
DOI:10.1002/anie.201405834
日期:2014.9.1
groups enabling the formation of CCbonds during the ester formation would be of significant interest. Reported herein is such asymmetric carbonyl carboacylation of aldehydes and ketones, thus affording complex bicyclic lactones in excellent enantioselectivities. The rhodium(I)‐catalyzed transformation is induced by an enantiotopicCC bond activation of a cyclobutanone and the formed rhodacyclic intermediate
Double Intramolecular Transacetalization of Polyhydroxy Acetals: Synthesis of Conformationally-Restricted 1,3-Dioxanes with Axially-Oriented Phenyl Moiety
作者:Samuel Asare-Nkansah、Bernhard Wünsch
DOI:10.3390/molecules21111503
日期:——
diethyl 3-hydroxyglutarate (15), benzaldehyde acetal 12a and acetophenone ketal 12b bearing a protected 1,3,5-trihydroxypentyl side chain in the o-position were prepared. The first acid-catalyzed intramolecular transacetalization gave a mixture of diastereomeric 2-benzofurans 18 (ratio of diastereomers 2:2:1:1). After OH group deprotection, the second intramolecular transacetalization afforded tricyclic alcohol