Fig 4
From: Oxidative coupling of sp 2 and sp 3 carbon–hydrogen bonds to construct dihydrobenzofurans
Applications of the oxidative coupling reaction protocol. a Path 1. Synthesis of (R)-1i: 10, (S)-11, PPh3, Et3N, DIAD, THF, N2, 25 °C, 16 h, 85% isolated yield; LiOH·H2O, THF/H2O, 80 °C, 12 h, 93% isolated yield. i) CDC conditions: Pd(OAc)2, 1,4-BQ, Ag2CO3, Acridine, KH2PO4, NaOAc, tAmylOH, air, 140 °C, 24 h; MeI, K2CO3, DMF, 50 °C, 12 h. 60% isolated yield over two steps, 97% ee. Path 2. Synthesis of (S)-1i: Benzoic Acid, (S)-11, PPh3, Et3N, DIAD, THF, N2, 25 °C, 12 h, 90% isolated yield; NaOH, MeOH, reflux, 12 h, afford (R)-11, 95% isolated yield; 10, (R)-11, PPh3, Et3N, DIAD, THF, N2, 25 °C, 16 h, 85% isolated yield; LiOH·H2O, THF/H2O, 80 °C, 12 h, 95% isolated yield. i) CDC conditions: Pd(OAc)2, 1,4-BQ, Ag2CO3, Acridine, KH2PO4, NaOAc, tAmylOH, air, 140 °C, 24 h; MeI, K2CO3, DMF, 50 °C, 12 h. 62% isolated yield over two steps, 98% ee. b ii) 10, 12, PPh3, Et3N, DIAD, THF, N2, 25 °C, 16 h, 60% isolated yield; LiOH·H2O, THF/H2O, 80 °C, 12 h, 73% isolated yield. iii) CDC conditions: Pd(OAc)2, 1,4-BQ, Ag2CO3, Acridine, KH2PO4, NaOAc, tAmylOH, air, 140 °C, 24 h; 4-Nitrobenzyl bromide, K2CO3, DMF, 50 °C, 12 h. 44% NMR yield over two steps. c iv) 10, 14, PPh3, DIAD, THF, 25 °C, N2, 16 h, 74% isolated yield; TBAF, THF, rt, 80% isolated yield; 15, PPh3, DIAD, THF, 25 °C, N2, 16 h, 70% isolated yield; LiOH·H2O, THF/H2O, 80 °C, 12 h, 86% isolated yield. v) CDC conditions: Pd(OAc)2, 1,4-BQ, Ag2CO3, Acridine, KH2PO4, NaOAc, tAmylOH, air, 140 °C, 24 h. c. MeI, K2CO3, DMF, 50 °C, 12 h. 52% NMR yield over two steps
