java (Hive Bee) 06-08-04 20:34 No 512226				Question: halogenating cinnamyl alcohol
						In halogenating the OH functional group in Cinnamyl Alcohol,   will it take preference over the double bond between C1-C2? As I want to reduce OH to CH3 without touching the double bond.  I have in mind to try the addition of a halogen and amino group at C1 C2...... java We're  all in this world together, http://www.aztlan.net
		Rhodium (Chief Bee) 06-09-04 00:32 No 512247				HX will add across the alkene
						You can oxidize the cinnamyl alcohol to cinnamaldehyde and reduce its tosylhydrazone with NaBH4 to allylbenzene: ../rhodium /cinnamaldehyde.html You cannot halogenate cinnamyl alcohol with any HX acid without touching the double bond. The Hive - Clandestine Chemists Without Borders
		Kinetic (Hive Bee) 06-09-04 16:21 No 512398				Cinnamyl alcohol to propenylbenzene
						This contradictory response was started last night, before it became contradictory. There are numerous literature references for the SN2 substitution of the OH in cinnamyl alcohol for chloride, bromide and iodide, using HCl, HBr and HI respectively. In fact, HI can go on to reduce the alkyl iodide to give the ever-usable propenylbenzene in one-pot. The substitution works probably because of the conjugation of the molecule, which gives a greatly stabilised transition state for the SN2 displacement (much like the rate enhancing effects when a leaving group is alpha- to a ketone). The addition across the double bond happens at its usual (slower) rate; addition across the double bond also disrupts the favourable conjugation. Because of these effects, the -OH of cinnamyl alcohol behaves effectively like the reactive -OH of benzyl alcohol. I would suggest adding HBr to cinnamyl alcohol to give cinnamyl bromide, followed by reduction to propenylbenzene with borohydride/PTC. Many reductions give a mixture of products (e.g. allylbenzene/propenylbenzene/propylbenzene) but with a suitable hydride nucleophile you can selectively displace the bromide with hydride (again, this may be made easier because of the conjugation stabilising the transition state). Here are some references (some of which are available online for free). Some of them look very interesting: Cinnamyl chloride from cinnamyl alcohol with HCl J.Amer.Chem.Soc. 107 (7), 1985, 2033-2046 Chem.Ber., 39, 1906, 2553 Arch.Pharm.(Weinheim Ger.), 247, 1909, 349 J.Org.Chem., 42, 1977, 871-875 Justus Liebigs Ann. Chem., 479, 1930, 211, 248 J.Chem.Soc., 1941, 507, 510. Cinnamyl chloride from cinnamyl alcohol using other sources of chloride SOCl2, 94% yield: Org.Lett., 5 (8), 2003, 1167-1170 PPh3/trichlorocyanuric acid: Synth.Commun., 32 (17) 2002, 2691-2694 Trichlorocyanuric acid/DMF/DCM, 92% yield: Org.Lett. 4 (4), 2002, 553-556 SOCl2/benzotriazole, 100% yield: Syn.Lett., 11, 1999, 1763-1765 Potassium carbonate/chlorotrimethylsilane, 91% yield: Synthesis, 4, 1983, 314-315 [Article in German]. Cinnamyl bromide from cinnamyl alcohol with HBr J.Amer.Chem.Soc. 38, 1916, 1076 Chem.Ber., 58, 1925, 280 J.Org.Chem., 25, 1960, 1719-1722 J.Chem.Soc., 97, 1910, 426 Chem.Ber. 39, 1906, 2553. Cinnamyl bromide from cinnamyl alcohol using other sources of bromide PBr3: Chem.Ber. 43, 1910, 178 NaBr/BF3/acetonitrile (79% yield): Tetrahedron Lett., 26 (32), 1985, 3863-3866 Hexamethyldisilane/pyridinium bromide perbromide (100% yield): J.Org.Chem. 45 (9), 1980, 1638-1639 Chlorotrimethylsilane/lithium bromide (93% yield): J.Org.Chem., 45 (9), 1980, 1638-1639. Cinnamyl iodide from cinnamyl alcohol with HI Justus Liebigs Ann. Chem. 479, 1930, 211, 248. Cinnamyl alcohol to propenylbenzene with HI Chem.Ber., 11, 1878, 671. Reduction of cinnamyl bromide to propenylbenzene NaBH4/PTC, 80% yield: J.Org.Chem., 46 (19), 1981, 3909-3911 Lithium tri-sec butyl borohydride, 99% yield: Bull.Chem.Soc.Jpn., 58 (2), 1985, 789-790 Zn(BH4)2, 60% yield: Angew.Chem., 95 (7), 1983, 568-569 [Article in German] LiAlH(i-Bu)2(n-Bu), 95% yield: J.Org.Chem. 49 (10), 1984, 1717-1724.
		java (Hive Bee) 06-09-04 17:35 No 512413				Question: halogenating cinnamyl alcohol
						Rhodium... thanks for the info on going to the allylbenzene from the OH and the many other references and comments you've been providing, they are most helpful in teach me good chemistry.   Kinetic  thanks for the info as I see it I have a good way to go to the CH3 and also to a CX from the OH. As I 've bee looking at the dialkylamino -chloro addition to the non conjugated cinnamyl chloride ../rhodium/pdf /archive/vinylic.aminochlorination.pdf  , for which I feel the chlorine can be removed with hydrogenation and end up with desired product ,except a dimethylamine as oppose to a methylamine on the C2. Saludos, from Latin America....java http://www.aztlan.net