Water → HCID 18370001, compound

Participants

Reaction Steps

23 ml of a 20% suspension of potassium hydride in oil (containing about 3.7 g/92 mmol KH) were pipetted into a 500 ml round flask provided with a magnetic stirrer and dropping funnel having a fitted argon bubble counter and washed three times with 10 ml of hexane each time. Then, 120 ml of tetrahydrofuran were added thereto and a solution of 25.0 g (83 mmol) of 2,2,4,6,6-pentamethyl-5,6,7,7a-tetrahydro-5-trimethylsilylmethyl-1,3-benzodioxol-5-ol in 220 ml of tetrahydrofuran was added dropwise thereto at room temperature and the mixture was stirred at room temperature for 30 minutes (GC control: educt no longer present). Then, the mixture was cooled to 0° C. and 50 ml of water were slowly added dropwise. An analogous working up to that in (i) gave 29.7 g of crude 2,2,4,6,6-pentamethyl-5,6,7,7a-tetrahydro-5-methylidene-1,3-benzodioxol as a yellowish oil. A distillation on a very short Vigreux column gave at a boiling temperature of 50° C./0.02 mbar (2 Pa) 15.6 g (90% yield) of pure product as a colorless oil. 1H-NMR (CDCl3, 250 MHz): inter alia 1.12 and 1.23 (2s, in each case 3H, C(6)—(CH3)2), 1.50 and 1.53 (2s, in each case 3H, C(2)(CH3)2), 1.73 (s, 3H, C(4)—CH3), 4.55 (m, 1H, CH—O—), 4.79 (d, J=6 Hz, ═CH2); IR (film): 1693, 1112 cm−1; mass spectrum: 208 (M+, 40), 107(100);

Provenance & Evidence