Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The product...Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.展开更多
Direct asymmetric aldol additions of acetone/and butanone to a-ketoesters were achieved using L-proline as a chiral catalyst. Various optically active a-hydroxyesters were obtained in the yields of 43%-93% with enanti...Direct asymmetric aldol additions of acetone/and butanone to a-ketoesters were achieved using L-proline as a chiral catalyst. Various optically active a-hydroxyesters were obtained in the yields of 43%-93% with enantioselectivities up. to 81% e.e. The steric effect seems to be an important factor which influences the activity and the selectivity of the reaction. Acetone showed higher reactivity than butanone while the latter provided better enantioselectivity in some cases.展开更多
A Lewis acid-catalyzed[4+2]cycloaddition of 3-alkyl-2-vinylindoles withβ,γ-unsaturatedα-ketoesters has been established in the presence of Sc(OTf)3,which afforded a series of indole-containing pyran derivatives in ...A Lewis acid-catalyzed[4+2]cycloaddition of 3-alkyl-2-vinylindoles withβ,γ-unsaturatedα-ketoesters has been established in the presence of Sc(OTf)3,which afforded a series of indole-containing pyran derivatives in generally good yields(up to 90%yield)with excellent diastereoselectivities(up to >95:5 dr)under mild conditions.This approach not only enriches the chemistry of 3-alkyl-2-vinylindoles,but also has provided an atom-economic method for the synthesis of indole-containing pyran derivatives with potential bioactivity.展开更多
Interesting and diverse tautomerizations and intramolecular hydrogen bondings of the chiral α-nitroester, α-nitrosoester and α-ketoester are described and rationally interpreted.
Melamine-formaldehyde resin supported H~＋ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives usi...Melamine-formaldehyde resin supported H~＋ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives using conventional heating and microwave irradiation in excellent yields with good purity.展开更多
基金support from the Research Council of Mazandaran University
文摘Pyridinium bromochromate has been found to be a highly efficient and selective reagent for the α-monobromination of 1,3- diketones and β-keto-esters in the absence of base, Lewis acid, or other catalyst. The products were formed in high to excellent yields under mild reaction conditions and in short reaction times.
文摘Direct asymmetric aldol additions of acetone/and butanone to a-ketoesters were achieved using L-proline as a chiral catalyst. Various optically active a-hydroxyesters were obtained in the yields of 43%-93% with enantioselectivities up. to 81% e.e. The steric effect seems to be an important factor which influences the activity and the selectivity of the reaction. Acetone showed higher reactivity than butanone while the latter provided better enantioselectivity in some cases.
基金This work was supported by National Natural Science Foundation of China(No.21772069)Natural Science Foundation of Jiangsu Province(No.BK20201018)+1 种基金Undergraduate Students Project of Jiangsu Province(No.202010320050Z)High-level Innovative and Entrepreneurial Talents Introduction Plan of Jiangsu Province,and Natural Science Foundation of JSNU(No.19XSRX010).
文摘A Lewis acid-catalyzed[4+2]cycloaddition of 3-alkyl-2-vinylindoles withβ,γ-unsaturatedα-ketoesters has been established in the presence of Sc(OTf)3,which afforded a series of indole-containing pyran derivatives in generally good yields(up to 90%yield)with excellent diastereoselectivities(up to >95:5 dr)under mild conditions.This approach not only enriches the chemistry of 3-alkyl-2-vinylindoles,but also has provided an atom-economic method for the synthesis of indole-containing pyran derivatives with potential bioactivity.
文摘Interesting and diverse tautomerizations and intramolecular hydrogen bondings of the chiral α-nitroester, α-nitrosoester and α-ketoester are described and rationally interpreted.
文摘Melamine-formaldehyde resin supported H~＋ is used as an efficient catalyst in the Pechmann condensation reaction of phenols withβ-ketoesters,in solvent-free media leading to the formation of coumarin derivatives using conventional heating and microwave irradiation in excellent yields with good purity.
