α-Selective Allylation of Isatin Imines Using Metallic Barium
作者:Akira Yanagisawa、Seiya Yamafuji、Toshiki Sawae
DOI:10.1055/s-0035-1561450
日期:——
Barbier-type allylation of isatin imines with allylicchlorides was achieved by using metallic barium as the promoter. Various α-allylated 3-amino-2-oxindoles were synthesized from the corresponding allylicchlorides and isatin imines. The double-bond geometry of allylicchlorides was retained throughout the reaction. An arylic bromide or iodide functionality of the products was robust to metalation under the
Tin powder-promoted one-pot synthesis of 3-spiro-fused or 3,3′-disubstituted 2-oxindoles
作者:Juanjuan Wang、Danfeng Huang、Ke-Hu Wang、Xiansha Peng、Yingpeng Su、Yulai Hu、Ying Fu
DOI:10.1039/c6ob01487a
日期:——
oxindoles has been developed from one-pot reactions of isatins, hydrazides or aromatic amines, 2-(bromomethyl)acrylic ester and tin powder in the presence of a catalytic amount of Brønsted or Lewis acid. The method avoids the use of toxic stannanes and allows easy operation. It is also proved that hydrazides are more favorable for intramolecular cyclization than amines.
Control of N-Heterocyclic Carbene Catalyzed Reactions of Enals: Asymmetric Synthesis of Oxindole-γ-Amino Acid Derivatives
作者:Xiang-Yu Chen、Jia-Wen Xiong、Qiang Liu、Sun Li、He Sheng、Carolina von Essen、Kari Rissanen、Dieter Enders
DOI:10.1002/anie.201708994
日期:2018.1.2
A strategy to control the switch between a non‐cycloaddition reaction and a cycloaddition reaction of enals, using N‐heterocyclic carbene (NHC) catalyisis, has been developed. The new scalable protocol leads to γ‐amino‐acid esters bearing a tetrasubstituted stereocenter in good yields and high stereoselectivities by homo‐Mannich reactions of enals and isatin‐derived ketimines. By simply changing the
In pole position: A simple and efficient approach to spirocyclic γ‐lactam oxindoles by the N‐heterocyclic carbene catalyzed addition of homoenloate equivalents to N‐aryl isatinimines has been developed (see scheme). The use of N‐aryl isatinimines as electrophiles in the NHC‐catalyzed umpolung reaction of α,β‐unsaturated aldehydes is demonstrated for the first time.
Catalytic Enantioselective Synthesis of Chiral 3-Amino-2-oxindoles by a Mannich Approach
作者:Akira Yanagisawa、Naoyuki Kushihara、Takuya Sugita、Moe Horiguchi、Kazuki Ida、Kazuhiro Yoshida
DOI:10.1055/s-0035-1560636
日期:——
A catalytic enantioselective Mannich-type reaction of a cyclohexanone-derived alkenyl trichloroacetate with isatin imines was achieved using an ( S )-BINOL-derived chiraltin dibromide possessing a 4- tert -butylphenyl group at 3- and 3′-positions as the chiral precatalyst in the presence of sodium methoxide, sodium iodide, and methanol. Optically active 3-alkylated 3-amino-2-oxindoles having up to