反应详情

As depicted in Scheme 3, catechol was cyclized with acetone under catalytic conditions, affording the corresponding 2,2-dimethylbenzo[d]1,3-dioxolane (C1). Intermediate (C1) was then treated with for example lead tetraacetate ubder acidic conditions, yielding the corresponding 2,2-dimethylbenzo[3,4-d]1,3-dioxolan-5-yl acetate (C2). Intermediate (C2) was then deprotected with strong base, providing a phenolic intermediate (C3), which was in turn reacted with intermediate (B5), as taught in scheme 2, affording a compound of formula I. Example 3 set forth below describes in detail the method by which compounds of formula I were prepared as shown in scheme 3.