Armed-disarmed concept disarming effect

The classic armed-disarmed approach, developed by Fraser-Reid, has created a solid basis for extensive studies and applications, and all strategies discussed in this section are related to (or derived from) this elegant concept. The key factor for the armed-disarmed activation to take place is the availability of a suitable promoter that differentiates between the armed and disarmed building blocks. While in most cases the differentiation of the reactivity between armed and disarmed species is maintained by the choice of promoter or temperature, the solvent effect observed by Oscarson may become a useful technique for future assemblies.160 Thus, it was demonstrated that highly reactive substrates could be activated in diethyl ether, whereas poorly reactive disarmed derivatives had to be activated in CH2CI2. 

Fraser-Reid s early work with armed/disarmed NPGs quantified effects that were already known at the time, but had not been effectively exploited for glycosylation chemistry [79-81]. Subsequent to the work with NPGs, similar effects were recorded for other donors. The concept has been extended well... 

Crich D, Li M (2007) Revisiting the armed-disarmed concept the importance of anomeric configuration in the activation of S-benzoxazolyl glycosides. Org Lett 9 4115-4118 Jensen HH, Bols M (2006) Stereoelectronic substituent effects. Acc Chem Res 39 259-265... 

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