The following reaction proceeds in two parts. The first part produces an intermediate compound A and byproduct HCOO-. The product of the second part is a bicyclic ?,?-unsaturated carbonyl compound.
Identify intermediate A, which has a molecular formula of C10H16O2, and give a curved-arrow mechanism for the transformation of A to the final product. Details count! Show ALL lone pairs of electrons and formal charges. Once you have supplied the organic intermediate A, do not add or remove atoms for the rest of the steps (i.e., atom conservation). If a CHx group is being deprotonated, draw all H\'s on the reacting site.