Fig. 4: Gram-scale reaction and further transformations.
From: Asymmetric formal C–C bond insertion into aldehydes via copper-catalyzed diyne cyclization
Reagents and conditions: (i) KOH (3 equiv), EtOH/THF = 1/1, 50 °C, 0.5 h. (ii) NBS (2.1 equiv), THF, 0 °C, 0.5 h. (iii) Boc2O (4 equiv), 4-DMAP (0.5 equiv), MeCN, 40 °C, 1 h. (iv) NaBH4 (2 equiv), MeOH/THF = 1/1, rt, 0.5 h. (v) BnNH2 (4 equiv), NaBH3CN (4 equiv), AcOH (3.3 equiv), MeOH/THF = 1/1, rt, 2 h. (vi) DNPH (5 equiv), EtOH/DCE/AcOH = 1/1/1, 80 °C, 1.5 h. (vii) Ph3PMeBr (2 equiv), nBuLi (2 equiv), THF, −78 °C–rt, 2 h.
