iodoalkynes from aldehydes; iodoalkynes
Submitted Jul 03, 2001, published Jul 03, 2001
Triphenylphosphine (1.15g, 4mmol)
Iodoform (1.65g, 4.2mmol)
Potassiumtbutoxide (1.569g, 12mmol)
Cinnamaldehyde (0.252mL, 2mmol)
THF (dry, 20mL)
To iodoform stirring in THF is added triphenylphosphine and 1 equivalent of potassiumtbutoxide and the brown mixture is stirred for 1 minute. Cinnamaldehyde is added and the reaction stirred for 15 minutes, then cooled to -78C. The remaining potassiumtbutoxide is then added and the reaction stirred until completion (TLC immediately after the second addition of potassiumtbutoxide in order to ascertain which spot is the intermediate) then quenched with brine, extracted twice with ether, dried over magnesium sulphate, filtered, concentrated and purified by colummn chromatography eluting with 10% Et2O/PE.
A:13CNMR (CDCl3, 75MHz) 8.1, 93.4, 108.1, 126.3, 128.8, 128.9, 135.4, 143.4.
B:1HNMR (CDCl3, 300mHz) d 4.71 (1H, t, J=6.2), 4.03 (1H, dd, J=6.4, 8.1), 3.82 (1H, dd, J=6.2, 8.1), 1.37 (3H, s), 1.25 (3H, s).
Michel P., Rassat A. Tetrahedron Lett. 1999 p.8579
Hirama M., Iguchi S., Wang G.X. J. Org. Chem. 2001 p.2146
Keywords: iodoalkyne, alkyne, diiodoalkene, aldehyde, ylid, Speziale, Wittig, isotopically labelled compounds