| Abstract [eng] |
In this work, new 1,2-oxazetidines, having Ts-, Boc- and Cbz-protecting groups have been synthesized. For the first time, structural features of N-tosyl-1,2-oxazetidine in solid phase were examined in detail by single crystal X-ray analysis. A hitherto unknown ring-opening reactivity of 1,2‐oxazetidine towards nucleophiles has been investigated. When reacted with organometallic compounds, this reagent provides electrophilic oxygen with a nitrogen‐terminated two‐carbon‐atom tether. The synthetic versatility of the products obtained was demonstrated in various transformations, leading to efficient synthesis of six‐, seven‐, and eight‐membered heterocyclic systems of pharmaceutical importance. We disclosed the preparation and synthetic applications of a new self-protected dimeric sulfenamide reagent, N-tosyl-1,5,2,6-dithiadiazocane, for the efficient and concise synthesis of medium-ring S,N-heterocycles from simple starting materials. High reactivity towards various nucleophiles, very clean reaction profile and the waste-free nature of this reagent enable the realization of one-pot synthetic procedures to access (benzo)thiomorpholines and 2,3-dihydro-1,4-thiazine derivatives in high yield. Chemoselective acidic hydrolysis of sulfonamides with trifluoromethanesulfonic acid has been evaluated as a deprotection method and further extended to more complex synthetic applications. In contrast to conventional troublesome sulfonamide hydrolysis, a near-stoichiometric amount of acid was found to be sufficient to bring about efficient deprotection of various neutral or electron-deficient N-arylsulfonamides, whereas electron-rich substrates provided sulfonyl group migration products. The deprotection method developed is fully selective for N-arylsulfonamides, and the possibility to discriminate among various different sulfonamides is demonstrated. |
