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50816-20-1 Synthesis

50816-20-1
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1066-54-2
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10-(Tetrahydro-2H-pyran-2-yloxy)-1-decyne

19754-58-6
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Yield:19754-58-6 92%

Reaction Conditions:

Stage #1: trimethylsilylacetylenewith n-butyllithium in tetrahydrofuran;cyclohexane at -60 - 0; for 0.5 h;
Stage #2: 2-(8-bromooctyloxy)tetrahydropyranwith N,N,N,N,N,N-hexamethylphosphoric triamide in tetrahydrofuran;cyclohexane at -20 - 20; for 19 h;
Stage #3: with tetrabutyl ammonium fluoride in tetrahydrofuran at 20; for 48 h;

Steps:

3.1.12. 6-(1-Heptyl-1H-1,2,3-triazol-4-yl)hexanoic acid (14) (Scheme 3)

General procedure: 3,4-Dihydro-2H-pyran (1.40g, 16.0mmol) was added to stirred solution of 6-bromo-1-hexanol (33a) (2.0g, 11.0mmol) and camphorsulfonic acid (116mg, 5mol%) in Et₂O at room temperature overnight. The reaction was basified with satd K₂CO₃ and extracted into Et₂O, washed with brine and dried over Na₂SO₄. Purification by flash column chromatography; neat CH₂Cl₂ gave 2-((6-bromohexyl)oxy)tetrahydro-2H-pyran (34a) (2.70g, 95%) as a colourless oil. ¹H NMR [DMSO] δ 4.55-4.50 (m, 1H), 3.72 (ddd, J=11.2, 8.1, 3.1Hz, 1H), 3.61 (td, J=9.7, 6.7Hz, 1H), 3.52 (t, J=6.7Hz, 2H), 3.46-3.37 (m, 1H), 3.35-3.28 (m, 1H), 1.84-1.76 (m, 2H), 1.73-1.64 (m, 1H), 1.64-1.54 (m, 1H), 1.54-1.28 (m, 10H). HRMS (ESI⁺) Calcd for C₁₁H₂₁BrNaO₂: 287.0617; (MNa⁺) 287.0613n-Butyllithium (2.07mL of a 2.0M solution in cyclohexanes, 4.1mmol) was added dropwise to a solution of trimethylsilylacetylene (0.60mL, as a solution in THF, 4.1mmol) in THF (8mL) at -60°C, then the reaction was allowed to warm to 0°C for 30min.¹² The reaction was then cooled to -20°C, HMPA (2mL) was added dropwise followed by 34a (1.0g, 3.8mmol). The reaction was stirred for 5h at 0°C and room temperature for an additional 14h, then quenched with satd NH₄Cl and extracted into EtOAc, washed with brine and dried over Na₂SO₄. The crude oil was filtered through a pad of silica with CH₂Cl₂ and concentrated to dryness to give (by ¹H NMR) a 2:1 mixture of trimethyl-(8-((tetrahydro-2H-pyran-2-yl)oxy)oct-1-yn-1-yl)silane (35a) and 2-(oct-7-yn-1-yloxy)tetrahydro-2H-pyran (36a) (1.0g, 98%). This (1.0g, 3.8mmol) was taken up in THF (10mL) and stirred with TBAF (5.6mL as a 1molL^-1 solution in THF, 5.6mmol) at room temperature for 48h. The reaction was diluted with EtOAc, and washed with satd NaHCO₃, brine, dried over Na₂SO₄ and concentrated to dryness to give only 36a (740mg, 91%) as a colourless oil.

References:

Marshall, Andrew J.;Lin, Jian-Ming;Grey, Andrew;Reid, Ian R.;Cornish, Jillian;Denny, William A. [Bioorganic and Medicinal Chemistry,2013,vol. 21,# 14,p. 4112 - 4119]

110-87-2 Synthesis