Ring expansions silver® nitrate

When 5-methylene-2,3,4,5-tetrahydro-1 -benzothiepine (111) was subjected to ring expansion reaction conditions (treatment with silver nitrate in the presence of iodine in methanol), intramolecular attack by sulfur at the initially formed halomethyl group led to the bicyclo[3.2. Ijoctane intermediate (112), which yielded the benzothiophene derivative (113) without formation of any ring expansion products (Scheme 15) <89TL4279>. 

The silver-nitrate-catalysed cyclopropyl-allyl rearrangement of (451) has been used in the preparation of benzazocines and, by ring expansion of (452) with silver acetate-acetic acid, the two substituted trflns,cis-cyclonona-dienes have been made. The trans,trflns-cyclodecadienes (454), which are involved in a synthesis of cyclodeca l,6-diyne-3,8-diol, have been prepared by... 

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