Dimethyl Sulfate → Methoxy(3-methoxyphenyl)methylene adamantane

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Reaction Steps

A quantity (11.3 g, 0.042 mol) of 3-methoxyphenyl adamant-2-yl ketone obtained according to Example 1 was suspended in 90 ml of molecular sieve-dried (3 Å) dimethylsulfoxide (DMSO). Heat was applied to dissolve the suspended solid. Upon cooling to room temperature with stirring, a fine suspension was formed. Potassium tertbutoxide (8.5 g, 0.070 mol) was added under an argon atmosphere. After 5 minutes, a nearly homogenous orange solution resulted, which was placed in a water bath at 50° C. Dimethyl sulfate (4 ml, 0.042 mol) was added dropwise by syringe over a period of 10 minutes. After 15 minutes of further stirring, an additional 3.3 ml of dimethyl sulfate (0.034 mol) was added in the same fashion. Subsequently, the colorless solution was stirred overnight at room temperature. After cooling in an ice bath, 0.5 g of K2CO3 and 125 ml of ice water added and the mixture extracted with three 50 ml portions of ethyl acetate. The combined organic fractions were washed with three portions of water, once with 50 ml of saturated aqueous NaCl solution, and dried over K2CO3. The solvent was removed in vacuo to yield an oil. The oil was dissolved in hexane, and the resulting solution filtered through Celite and concentrated in vacuo to provide 11.5 g (96% yield) of a viscous, straw-colored oily substance. TLC indicated a clean conversion to an enol ether (Rf 0.68; E. Merck Al2O3 --CH2Cl2 : hexanes--50:50) with a trace of the ketone starting material. The oil was distilled from K2CO3 (b.p. 148°-150° C., 0.25 mm Hg). Under these conditions, slight yellowing occurred in the still head. I.R. analysis of this distillate revealed a small ketone absorption band at 1670 cm-1. I.R. (CH2Cl2): 2900 cm-1, 1670 cm-1 (weak) 1600 cm-1, 1590 cm-1, 1580 cm-1, 1570 cm-1, 1095 cm-1, 1080 cm-1 ; 1H-NMR 60 MHz (CDCl3): δ 1.5-2.0 (m, 12H), δ 2.55 (s, 1H), δ 3.2 (s, 1H), δ 3.25 (s, 3H), δ 3.75 (s, 3H), and δ 6.7-7.3 (m, 4H). These data confirmed that the structure of the product was: ##STR25##

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