Carbocyclic compounds Mannich reaction

Attachment of a base-bearing side chain to the carbocyclic ring of a benzodioxan gives another compound that acts as an a-adrenergic blocker. Mannich reaction of the methyl ketone in (61-2), obtainable by acetylation of the benzodioxan proper (61-1), with phenylpyrrolidine (61-3) and formaldehyde leads directly to proroxan (61-4) [71]. 

The compounds obtained by the replacement of ring sulfur by carbon, as in the case of penicillins, show somewhat improved antibiotic properties. A free radical— based route has been described for the conversion of fermentation derived cephalosporins to their carbocyclic derivatives. The first step in this sequence consists of the condensation of the cephalosporin sulfone (36-1) with formaldehyde and dimethyla-mine the initial product from the Mannich-like reaction consists of the exomethylene derivative at the position adjacent to the activating sulfone. The product is treated in situ with phenylselenol to give the Michael adduct (36-2). This fragments with an extmsion of sulfur dioxide when heated with the free radical initiator AIBN in the presence of tributyltin hydride the reaction can be envisaged as leading to the... 

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