The Wrong Choice of Reaction Conditions How not to Prepare an

Attempts to carry out what are apparently trivial reactions can often lead to completely unexpected results. There are many causes of such anomalous reactions, but perhaps the most common is an injudicious choice of reaction conditions, as illustrated by the following example. 

The indole derivative 1 was heated under reflux in thionyl chloride for 5 hours, then excess of thionyl chloride was removed by distillation and the residue was treated with methanol. This did not, however, give the expected product, viz- the methyl ester of 1 instead, the product (63%) was shown to be the tricyclic compound 2. 

Suggest a mechanism for the formation of 2 from 1 under these conditions. 

A solution of 2-acetoxy-4-methylthio-3,5-xylenol 1 in benzene containing excess triethylamine and methyl isothiocyanate was heated under reflux for 18 hours in an attempt to prepare the N-methylthionocarbamate from 1. The product, however, which was formed in quantitative yield, was found to be 4-[(acetoxymethyl)thio]-3,5-xylenol 2 and it was shown that the same transformation occurred just as readily in the absence of the methyl isothiocyanate. 

Reaction of 4-methylsulphinyl-3,5-xylenol 1 in a 2 1 mixture of acetic anhydride-acetic acid at 100°C goes to completion within an hour and gives two products. The major product is 2-acetoxy-4-methylthio-3,5-xylenol 2 and the minor a crystalline solid A, (also) C11H14O3S. The 

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