2074 (1960). pointed out in an earlier paper. 2 We now present the experimental evidence which supports the assumption. Although Nazarov and his associatess reported that the dimerization of a dioxane solution of 2-methoxy-1, 3-butadiene at 180-190O gave l-methoxy- 4-(l-methoxyviny1)-1-cyclohexene (13, R= R '= H), it might be argued that the orientation of the Diels-Alder reaction may alter in the presence of an acid~ atalyst.~ This was found not ...