Preparation of 3-hydroxyoxindoles with dimethyldioxirane and their use for the synthesis of natural products

Preparation of (+)- and (−)- β-phenyl- and β-(4-chlorophenyl)-γ- butyrolactones: Key Intermediates in the Synthesis of β-phenyl-GABA and Baclofen

“…The preparation of 4 is also shown in Scheme 1. Thus, the p-chlorostyrene (12) was oxidized with dimethyldioxirane (DMD) generated in situ from oxone ® and acetone in a buffer of bicarbonates (pH 7) [13], to afford the p-chlorostyrene oxide (13) in 74% yield, which was reacted with the sodium salt of diethyl malonate in ethanol to give the α-carboethoxy-γlactones 14 and 15 in 24 and 7% yield, respectively. The solid phase decarboethoxylation of 14 with alumina/H 2 O afforded 4 in 64% yield.…”

“…The residue was separated by flash column chromatography on silica gel (CH 2 Cl 2 -EtOAc-acetone 210:90:1) to give, in sequence, pure (2'R,3S)-5 and (2'R,3R)-5 from 3 and (2'R,3S)-6 and (2'R,3R)-6 from 4. 3328,3246,3030,2973,1638,1554, 1450 cm −1 ; 1 H NMR (CDCl 3 , 400 MHz) δ 7.29-7.14 (10H, m, H-6 to H-10 and H-5' to H-9'), 6.28 (1H, d, J = 6.9 Hz, NH), 4.96 (1H, q, J = 6.9 Hz, H-2'), 3.70 (1H, dd, J = 11.0, 5.9 Hz, H-4A), 3.64 (1H, dd, J = 11.0, 7.4 Hz, H-4B), 3.52 (1H, br s, OH), 3.23 (1H, q, J = 6.9 Hz, H-3), 2.66 (1H, dd, J = 14.3, 7.4 Hz, H-2A), 2.43 (1H, dd, J = 14.3, 7.0 Hz, H-2B), 1.25 (3H, d, J = 7.0 Hz, C-3' Me); 13 C NMR (CDCl 3 , 100 MHz) δ 171.3 (C-1), 143.0 (C-4'), 141.6 (C-5), 128.6 and 128.4 (C-7, C-9 and C-6', C-8'), 127.6 (C-6, C-10), 127.0 and 126.8 (C-7'and C-8), 126.0 (C-5', C-9'), 66.8 (C-4), 48.7 (C-2'), 44.9 (C-3), 40. 3234,3031,2966,1645,1565, 1451 cm −1 ; 1 H NMR (DMSO-d 6 , 400 MHz,) δ 7.29-7.15 (8H, m, H-6 to H-10 and H-6' to H-8'), 7.03 (2H, dd, J = 7.7, 1.5 Hz, H-5', H-9'), 6.16 (1H, d, J = 8.1 Hz, NH), 4.99 (1H, q, J = 7.0 Hz, H-2'), 3.75 (1H, dt, J = 11.0, 5.5 Hz, H-4A), 3.69 (1H, dt, J = 10.6, 6.6 Hz, H-4B), 3.34 (1H, t, J = 5.9 Hz, OH), 3.25 (1H, q, J = 6.9 Hz, H-3), 2.71 (1H, dd, J = 14.3, 7.0 Hz, H-2A), 2.45 (1H, dd, J = 14.3, 7.0 Hz, H-2B), 1.37 (3H, d, J = 7.0 Hz, C-3' Me); 13 C NMR (DMSO-d 6 , 100 MHz) δ 171.2 (C-1), 142.8 (C-4'), 141.5 (C-5), 128.6 and 128.4 (C-7, C-9 and C-6', C-8'), 127.6 (C-6, C-10), 127.0 and 126.8 (C-7' and C-8), 126.0 (C-5', C-9'), 66.8 (C-4), 48.6 (C-2'), 44.9 (C-3), 40.3 (C-2), 21.…”

Catalytic Double Stereoinduction in Asymmetric Allylic Alkylation of Oxindoles

“…The Moc group is labile under the reaction conditions, and the deprotected amide can act as a catalyst poison. [21] Subsequent optimization revealed that the use of BSA as the stoichiometric base was compatible with the Moc group and afforded consistent conversion with only 2.5% catalyst loading (entry 8).…”

Diversified Synthetic Strategies for Pyrroloindoles: An Overview

“…Compound 53 was further treated with methyl amine (MeNH 2 ) at 25°C for 16 h to give oxindole 54 . Further, compound 54 was reduced using LiAlH 4 to afford debromoflustraminol 55 as depicted in Scheme .…”