Stable Aziridinium Salts as Versatile Intermediates: Isolation and Regio‐ and Stereoselective Ring‐Opening and Rearrangement

Song, Hyun Beom; Dadwal, Mamta; Lee, Yeseul; Mick, Emily; Chong, Hyun‐Soon

doi:10.1002/ange.200805244

Cited by 1 publication

(1 citation statement)

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“…The activation energy of this process calculated from the aziridine-SO 3 complex was DG°= 34.3 kcal mol À1 . This activated aziridinium cation [26] could undergo a regioselective ring-expansion reaction into the corresponding oxazolinium cation (tsRE, DG°= 11.7 kcal mol À1 ) together with the ring-opening reaction with methanol at both the secondary (tsS N 2ab, b-attack, DG°= 21.8 kcal mol…”

Section: Wwwchemeurjorgmentioning

confidence: 99%

A Novel Multistep Mechanism for the Stereocontrolled Ring Opening of Hindered Sulfamidates: Mild, Green, and Efficient Reactivity with Alcohols

Jiménez‐Osés

Avenoza

Busto

et al. 2009

Chemistry A European J

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Cyclic hindered sulfamidates exhibited an outstanding performance in their ring-opening reactions with alcohols and in the absence of any external activator. The mechanism of this unprecedented transformation was thoroughly studied both experimentally and theoretically. As a result, a nontrivial stepwise pathway involving solvent-induced conversion of the sulfamidates to activated aziridinium and then to oxazolinium cations, which are finally opened at their 5-position with inversion of configuration, is proposed. The presence of the SO(3) moiety in the sulfamidate was revealed as a "built-in activator". In fact, the spontaneous SO(3) cleavage takes place under the reaction conditions and avoids the subsequent step of hydrolysis after the ring opening of the sulfamidates. This is another important improvement of this methodology with respect to the standard basic conditions, allowing a greater compatibility with other functional groups. Furthermore, the carbamate group plays a key role in this mechanism. Briefly, a highly chemoselective and stereoespecific formal solvolysis of hindered sulfamidates with alcohols without further activation is described. This reaction takes place exclusively at the quaternary center with inversion of configuration, providing a new straightforward synthetic route to O-substituted alpha-methylisoserines.

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Section: Wwwchemeurjorgmentioning

confidence: 99%