has been developed from the cyclization of 2‐propynyl‐1,3‐dicarbonyl compoundscatalyzed by potassium tert‐butoxide, copper(II) trifluoromethanesulfonate and triphenylphosphine using methanol/dichloromethane as the solvent under very mild conditions. Moreover, dihydrofurans could be easily transformed into the corresponding furans in the presence of trifluoroacetic acid.
type reaction of epsilon-acetylenic beta-keto esters to form highly functionalized methylenecyclopentanes are described. The observed regio-, chemo-, and stereoselectivities support a process of cycloisomerization which controls the relative stereochemistry of two contiguous stereogenic centers. An efficient route to the basic skeleton of the phyllocladane family has been achieved via a one-pot sequence
Iodine-Catalyzed Synthesis of Substituted Furans and Pyrans: Reaction Scope and Mechanistic Insights
作者:Domenic P. Pace、Raphaël Robidas、Uyen P. N. Tran、Claude Y. Legault、Thanh Vinh Nguyen
DOI:10.1021/acs.joc.1c00608
日期:2021.6.18
Substituted pyrans and furans are core structures found in a wide variety of natural products and biologically active compounds. Herein, we report a practical and mild catalytic method for the synthesis of substituted pyrans and furansusing molecular iodine, a simple and inexpensive catalyst. The method described is performed under solvent-free conditions at an ambient temperature and atmosphere,
Aerobic α-hydroxylation of β-keto esters and amides by co-catalysis of SmI3 and I2 under mild base-free conditions
作者:Shun-Ming Yu、Kai Cui、Fei Lv、Zhen-Yu Yang、Zhu-Jun Yao
DOI:10.1016/j.tetlet.2016.05.052
日期:2016.6
A clean base-free α-hydroxylation of β-keto esters and amides has been developed, in which air was used as the oxygen source and SmI3 and I2 were applied as the catalysts, affording the corresponding α-hydroxylated 1,3-dicarbonyl products in good to excellent yields undermildconditions. Mechanism discussion shows that both oxygen atoms of dioxygen are utilized and incorporated into the product through
La(OTf)3 catalyzed synthesis of α-aryl tetrasubstituted pyrroles through [4+1] annulation under microwave irradiation
作者:Xue-Min Tan、Qiao-Mei Lai、Zhi-Wei Yang、Xiao Long、Hai-Lin Zhou、Xiao-Lin You、Xiao-Jie Jiang、Hai-Lei Cui
DOI:10.1016/j.tetlet.2016.11.122
日期:2017.1
A La(OTf)3 catalyzedsynthesis of tetrasubstituted pyrroles undermicrowaveirradiation has been developed affording various α-aryl tetrasubstituted pyrroles in acceptable to good yields (36–82% yield) through condensation/alkyne azacyclization/isomerization sequence. Functionalized α-aryl pentasubstituted pyrroles could be prepared from tetrasubstituted pyrroles through easy transformations.