Reaktionsschritte
According to a general procedure for homologation, methoxymethyl triphenylphosphonium chloride (2.3 g, 6.62 mmol) in dry THF (18 mL), NaOtBu (0.797 g, 8.3 mmol), ketone 42 (0.655 g, 3.31 mmol) in THF (6 mL) were stirred at 0° C. Following the general workup, the mixture of enol ethers (0.398 g, 1.76 mmol) in THF/H2O (9:1, 6 mL) were hydrolyzed using Hg(OAc)2 (1.680 g, 5.28 mmol) at room temperature. After the general extraction procedure, aldehyde (0.300 g, 1.41 mmol) in MeOH (4 mL), Ohira-Bestmann reagent (0.407 g, 2.12 mmol) dissolved in MeOH (2 mL), powdered K2CO3 (0.410 g, 2.96 mmol) were stirred at 0° C. Following the general workup and flash chromatography (SiO2, 5 g, 5% EtOAc/hexanes) alkyne 45 was obtained as a white solid (0.066 g, 10% yield over 3 steps): TLC Rf=0.3 (5% EtOAc/hexanes); mp 75.4-76.7° C.; 1H NMR (500 MHz, CDCl3) δ 8.82 (s, 2H), 8.60-8.21 (m, 2H), 7.48-7.46 (m, 3H), 3.82 (qd, J=7.1, 2.5 Hz, 1H), 2.34 (d, J=2.5 Hz, 1H), 1.57 (d, J=7.2 Hz, 3H); 13C NMR (125 MHz, CDCl3) δ 163.7, 156.1, 137.6, 133.3, 130.9, 128.8, 128.3, 84.6, 71.9, 27.4, 23.8; IR (neat cm−1) 3205, 3059, 2978, 2934, 1584, 1547, 1425, 1296, 1175, 1094, 1069, 749, 692, 651; HRMS (DART, M++H) m/z 209.1103 (calculated for C14H13N2, 209.1079).
