Improved synthesis of 2-methoxypropene

Abstract

Notestracted with an ether-hexane mixture (3:1) and the combined extracts were dried over anhydrous magnesium sulfate. Preparative thin layer chromatography on silica gel afforded 165 mg (52%) of pure (±)-or-turmerone (1): rmax (CHClj) 1685 (0=0), 1620 (C=CH-), 1515 (-C,Hi-). 819 cm'1 (p-C6H4-); nmr (CCI4) 7.00 (s, 4 H, p-CHsCeHj-), 5.90 [m, 1 H, -CH=C(CH3)2], 3.20 [m, 1 H, C,H,CH(CH3)-], 2.50 (m, 2 H, -CH2C0-), 2.25 (s, 3 H, p-CH3C6H6-), 2.08 [s, 3 H, ~COCH=C(CH3)2, methyl cis to carbonyl], 1.81 [s, 3 H, -COCH=C(CH3)2, methyl trans to carbonyl], 1.20 [d, 3 , , , ^)-]; mje 216. The analytical sample was obtained as a colorless oil by preparative tie followed by molecular distillation, bp (bath) 90°( 0.07 mm).

An Efficient Synthesis of Functionalized Helicenes

“…One way to do this that works well (the yield was 89%) is to combine 19 with TMSOTf (Tf = triflate) and ( i -Pr) 2 EtN in CH 3 CN at room temperature . However, an even better way, because it does not require TMSOTf, which is expensive, is a modification of a procedure of Newman and Vander Zwan, who eliminated methanol from two acetals by heating them at 110−120 °C with succinic anhydride, benzoic acid, and pyridine in diglyme . The modified procedure uses chlorotrimethylsilane, benzoic acid, and pyridine; at 65 °C, it gives a yield of 78%.…”

Total synthesis of (.+-.)-N-methylmaysenine

“…alkyl) on the diene. [5][6] Trost's studies have provided important new margins of regiochemical control, using 2,3-7 (cf. 6) and 1,4-dihetero-substituted8 (cf.…”

An alternative synthesis of anomeric methyl 2-deoxy-4-thio-D-erythro-pentofuranosides

“…By modifying the reaction conditions, we were able to obtain a nearly quantitative yield of 2. Acetylation of 2, using acetic anhydride in pyridine, produced crystalline methyl 2,3-anhydro-4-0-acetyl-j3-L-lyxopyranoside (5) in quantitative yield. Treatment of compound 2 in a chloroform-benzene solution with 2 -methoxypropene,°i n the presence of a catalytic amount of hydrogen chloride, gave methyl 2,3-anhydro-4-0-(2-methoxyisopropyl)-/3-L-lyxopyranoside (4) in 94% yield.…”