Highly diastereoselective addition of photochemically generated radicals to (5R)-(−)-menthyloxy-2[5H]-furanone - synthesis of(−)-terebic acid
摘要:
Photochemically generated ketyl and 2-dioxdanyl radicals are added with high diastereoselectivity (de > 95%) to (5R)-(-)-5-menthyloxy-2[5H]furanone. This reaction is used for the asymmetric synthesis of (-)-terebic acid. The double bond is attacked by the radicals on the ul-side.
A novel, multimicrocapillary flow reactor (M mu CFR) was constructed and applied to a series of sensitized photoadditions involving 2(5H)-furanones. The reactor allowed for rapid and energy-, time-, and space-efficient sensitizer screening, process optimization, validation, scale-up, and library synthesis.
Photosensitized addition of isopropanol to furanones in a continuous-flow dual capillary microreactor
A novel continuous-flow photoreactor with parallel capillaries was constructed and successfully tested for the DMBP-sensitized addition of isopropanol to furanones. Complete conversions were achieved after a maximum of 10 min of irradiation with a single 350 nm lamp. The results were compared to analogous batch experiments using a conventional Rayonet chamber reactor equipped with 16 UVA lamps. The capillary tower generally showed higher space-time yields. (C) 2010 Elsevier Ltd. All rights reserved.
Stereoselective intermolecular addition of ketyl radicals generated from ketones by photoinduced electron transfer
作者:Cédric Brulé、Norbert Hoffmann
DOI:10.1016/s0040-4039(01)02089-5
日期:2002.1
Ketyl radicals were produced from ketones by photochemical electron transfer and subsequent proton transfer from tertiary amines. These radicals were stereoselectively added to (5R)-5-(-)-menthyloxy-2[5H]-furanone 1. Due to their low reactivity, the alpha -aminoalkyl radicals which were generated at the same time were not added to 1. The ketones were used in stoichiometric quantities. (C) 2001 Elsevier Science Ltd. All rights reserved.