An efficient synthesis of cycloalkane-1,3-dione-2-spirocyclopropanes from 1,3-cycloalkanediones using (1-aryl-2-bromoethyl)-dimethylsulfonium bromides: application to a one-pot synthesis of tetrahydroindol-4(5H)-one
摘要:
An efficient synthesis of cyclohexane- and cyclopentane-1,3-dione-2-spirocyclopropanes from 1,3-cycloalkanediones using sulfonium salts was achieved. The reaction of 1,3-cycloalkanediones with (1-aryl-2-bromoethyl)-dimethylsulfonium bromides and powdered K2CO3 in EtOAc provided the corresponding spirocyclopropanes in high yields. Furthermore, a one-pot synthesis of tetrahydroindol-4(5H)-one from 1,3-cyclohexanedione was achieved using the present protocol and a sequential ring-opening cyclization of spirocyclopropane with a primary amine. (c) 2015 Elsevier Ltd. All rights reserved.
The kinetics and the stereochemistry of alkalinecleavage of several 1,1-diacetyl-2-arylcyclopropanes (1) in ethanol-water mixture are reported. The rates can be expressed approximately by a third order equation, rate=k2[1][OH−]2. With para-substituted derivatives (p-CH3, H, p-Cl and p-Br) of 2-phenyl ring, the reaction constant ρ was obtained as +4.3 by plotting logk2 against normal Hammett σ. At