Indoles oxidations, sodium periodate

The synthesis of a C-labelled version of naratriptan (3b) is highlighted in Scheme The indole ring of naratriptan hydrochloride (3) was oxidatively cleaved using sodium periodate to give ketoformanilide 45. Cyanation of 45 with potassium [ C]cyanide in aqueous ethanol gave the intermediate amidine 46, which was reduced directly with NaBH4 in acetic acid to afford C-labelled naratriptan (3b), which was isolated as the hydrochloride salt. 

Oxidative cleavage of the indole 2,3-double bond can be achieved with ozone, sodium periodate, potassium superoxide, " with oxygen in the presence of cuprous chloride and with oxygen, photochemi-cally in ethanolic solution. ... 

Sodium periodate oxidations of several cycloalk[h]indoles and their JV-methyl analogues have been reported to give ring-expanded keto-lactams,... 

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