Grob Fragmentation of a 1-Azaadamantane

Treatment of the readily accessible 1-azaadamantane derivative 1 with thionyl chloride gave the mono-gem-dichloro derivative in 92% yield. Refluxing of a solution of the latter in aqueous ethanol containing triethylamine (3 eq.) gave 5-chloro-2,4,6-trimethylresorcinol in 62% yield in what has been claimed as the first example of a triple Grob fragmentation reaction. 

Azine oxides are versatile starting materials for heterocyclic synthesis and are frequently used for regioselective ring substitution reactions, most of which proceed with loss of the oxide substituent. Occasionally some unusual selectivities are observed. For example, treatment of 3-methoxypyrazine A-oxide with equimolar amounts of diethylcarbamoyl chloride and 4-methoxytoluene-a-thiol in refluxing acetonitrile gave 2-methoxy-6-(4-methoxybenzylthio)-pyrazine as the sole product in 60% yield. 

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