F 2-Pentyne

Pentyl methanesulfonate, 2545 f Pentyl nitrite, 1992 f 1-Pentyne, 1892 f 2-Pentyne, 1893... 

Nickel(II) cyanide, 0993 Nitrogen oxide, 4719 Nitrogen trichloride, 4137 Nitrogen triodide, 4628 Nitrosyl chloride, 4017 Nitryl chloride, 4019 Nitryl hypofluorite, 4298 Oxygen difluoride, 4311 f Pentaborane(9), 0188 f 1,4-Pentadiene, 1891 f 1,3-Pentadiene, 1890 f 1,2-Pentadiene, 1889 f 2-Pentyne, 1893 f 1-Pentyne, 1892... 

The study of the addition of trifluoroacetic acid to several 5-substituted 1-pentyne derivatives 22 led Peterson and Duddey (1963, 1966) and Peterson and Bopp (1967) to the conclusion that for some of the compounds investigated the intermediate resulting from protonation of the triple bond may be a five-membered ring cation of type 23, rather than a linear vinyl cation. This is indicated by the observation of rearranged products deriving from 1-5 shift when Y = Cl, F, OMe, and OAc (see scheme 3). Kinetio data indicate that Y-participation is important in the transition state of the reaction. Anchimeric assistance effects, expressed in terms of the ratio of assisted to unassisted mechanisms, kjjkg (Heck and Winstein, 1957), have been estimated to be 3 4 for Y = Cl and 6 5 for Y = OMe. The entire kinetic picture almost matches... 

O Donnell, J., L. Gerace, F. Leister and W. Soffer. (1975) "Chemical selection of mutants that affect alcohol dehydrogenase in Drosophila. II Use of 1-pentyn-3-ol." Genetics 79 73-83. 

A soln. of 1-pentyne in tetrahydrofuran treated sequentially with a soln. of 3,6-di-methylborepane in tetrahydrofuran at 0°, then 2 hrs. at 25°, with an ethereal soln. of methyllithium at -20°, and with allyl bromide at 25°, then refluxed 2 hrs., aq. 3 N NaOH added, and treated dropwise at 30-40° during 0.5 hr. with 30%-H202 l-octen-4-ol. Y 84%. F. e. s. G. Zweifel, R.P. Fischer, and A. Horng, Synthesis 1973, 37. 

Toward this end, aldehyde 2.188 was protected as the acetal, which was followed by oxidative removal of PMB group and subsequent TPAP oxidation of resulting alcohol to deliver the aldehyde 2.212. Gratifyingly, the subjection of 2.212 to the (-)-MlB-catalyzed asymmetric vinylation reaction (4-methyl-1-pentyne, Cy2BH, Et2Zn, (-)-MlB, toluene, -5 °C, 1.5 h) afforded the desired (17/f)-alcohol 2.213 with excellent stereoselectivity (dr = 32 1) as determined by HPLC. 

Sitter, K.D., Andersson, A., D Haen, J., Leysen, R., Mullens, S., Maurer, F.H.J., and Vankelecom, I.F.). (2008) Silica filled poly(4-methyl-2-pentyne) nanocomposite membranes similarities and differences with poly(1 -trimethylsilyl-1 -propyne)-silica systems./. Membr. Sd., 321 (2), 284-292. 

SCHEME 4. Synthesis of chromomoric acid B methyl ester [12], Reagents (i) lithium (8-f-butyldimethylsilyloxyoctyl), Cul, Et20 (ii) 1-iodo-2-pentyne, hexamethylphospho-ramide (HMPA) (iii) 5% LiOH, MeOH, tetrahydrofuran (THF) (iv) AcOH, THF, H2O (v) pyridium dichromate, A/,A/-dimethylformamide (DMF), molecular sieves (vi)... 

To an oven-dried reaction vial were added 11 mg Pd(OAc)2 (0.05 mmol), 47 mg l,l -bis(di-f-butylphosphino)ferrocene (0.1 mmol), and 346 mg potassium carbonate (2.5 mmol). The vial was purged with argon. Then 123 jxL 2-chloro-4-methylaniline (1 mmol), 192 xL 1-phenyl-l-pentyne (1.2 mmol), and 2 mL NMP were added via syringe. The reaction was heated to 130°C, stirred at the same temperature and monitored by HPLC. The reaction was complete after 4 h. The ratio of the regioisomer was 91 9. The mixture... 

Xenon difluoride added at 25 to a soln. of 1-phenyl-l-pentyne in methylene diloride, stirred, anhydrous HF as catalyst introduced, and the product isolated after 6 hrs. 1,1,2,2-tetrafluoro-l-phenylpentane. Y 55%. F. e. s. M. Zupan and A. Poliak, J. Org. Chem. 39, 2646 (1974). ... 

Ethyl-l-pentyn-3-ol added dropwise with stirring and ice-cooling to a mixture of excess coned. HCl, 0.5 mole of calcium chloride, 0.4 mole of CuCl, and some copper bronze powder, stirring continued 1 hr. at 0-5° 3-chloro-3-ethyl-l-pentyne. Y 83%.— This procedure gives higher yields and purer products than previous methods. F. e. s. G. F. Hennion and A. P. Boisselle, J. Org. Chem. 26, 725 (1961). 

Isopropylcyclohex-2-enone in a small amount of tetrahydrofuran added to a soln. of Li-hydridocuprate complex prepared from Cul-hydride and pentyn-1-yllithium in tetrahydrofuran, and stored 24 hrs. at -20 -> 2-isopropylcyclo-hexanone. Y 95%. F. e. s. R. K. Boeckman, Jr., and R. Michalak, Am. Soc. 96, 1623 (1974) also f. reactions with Li-hydridocuprate complexes S. Masamune, G. S. Bates, and P. E. Georghiou, ibid. 96, 3687. 

A soln. of l-phenyl-4,4-dimethyl-l-pentyn-3-one in anhydrous dimethyl sulfoxide injected at room temp, during 20 sec. into a stirred soln. of dimethylsulfoxo-nium methylid prepared from trimethylsulfoxonium iodide and NaH in dimethyl sulfoxide, stirring continued 17 hrs. at room temp, and 1.5 hrs. at 70° 1-methyl-3-phenyl-5-rerr-butylthiabenzene 1-oxide. Y 62.8-75.5%. F. e., also isolation of intermediates, s. A. G. Hortmann and R. L. Harris, Am. Soc. 93, 2471 (1971). 

Barluenga J, Dieguez F, Rodriguez F, Fananas FJ, Sordo T, Campomanes P (2005) [W(CO)5]-Catalyzed endo- or errtj-cycloisomerization reactions of 1,1-disubstituted 4-pentyn-l-ols experimental and theoretical studies. Chem-Eur J 11(19) 5735-5741. doi 10.1002/chem. 200500537... 

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