Compound C10
(3R,4S,5R,6S,7R,8R,9S,10R,11S,12R)-3,4,5,6,7,8,9,10,11,12-decamethyltetradeca-1,13-diyne
From: Odd–even alternations in helical propensity of a homologous series of hydrocarbons
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InChIKey NVCYUINUHNNOIR-WAFPNXIJSA-N
Compound data: NMR
Compound data: Crystallographic data
Synthetic procedure: See article for the definitive version of this procedure and for full experimental details.
Boronic ester 18 (70 mg, 0.13 mmol, 1.00 eq.) was alkynylated with vinyl carbamate 16 (56 mg, 0.33 mmol, 2.50 eq.), LDA (0.86 M in THF, 0.38 mL, 0.33 mmol, 2.50 eq.), iodine (82 mg, 0.33 mmol, 2.50 eq.) and LDA (0.86 M in THF, 0.76 mL, 0.65 mmol, 5.00 eq.) according to GP3 outlined for compound 19. The crude residue was purified by flash column chromatography (pure n-pentane) to give C10 (30 mg, 69%) as a white solid. . TLC: Rf = 0.38 (n-pentane:CH2Cl2 90:10). m.p.: 88 – 92 °C (acetonitrile). 1H NMR: (500 MHz, Toluene-d8) δ 2.24 (2H, dqd, J = 9.2, 6.9, 2.4 Hz, H3), 2.05 (2H, dqd, J = 8.6, 6.8, 3.3 Hz, H7), 1.85 (2H, d, J = 2.4 Hz, H1), 1.71 (2H, dqd, J = 9.2, 6.8, 3.3 Hz, H5), 1.62 (2H, m, H11), 1.52 (2H, dqd, J = 8.6, 6.8, 3.2 Hz, H9), 1.11 (6H, d, J = 6.9 Hz, H4), 0.87 (6H, d, J = 6.2 Hz, H12), 0.81 (6H, d, J = 6.8 Hz, H10), 0.77 (6H, d, J = 6.8 Hz, H8), 0.74 (6H, d, J = 6.8 Hz, H6) ppm. 13C NMR: (126 MHz, Toluene-d8) δ 88.7 (C2), 69.9 (C1), 38.8 (C5), 37.2 (C7), 35.7 (C9), 35.7 (C11), 30.1 (C3), 18.8 (C4), 12.0 (C10), 11.9 (C8), 11.8 (C12), 11.6 (C6) ppm. HRMS (m/z): (MALDI−) calc’d for C24H42 [M–H]–: 329.3214; found: 329.3210. IR (νmax): 3310, 2971, 2922, 2879, 1452, 1383, 1083 cm–1. [α]D23: +7 (CHCl3, c = 1.0).
