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IDCPS

Bielawska and Michalska [511] have introduced S-(2-deoxyglycosyl)phosphor-othioates as glycosyl donors. Activation of these compounds for glycosidation with silver salts (AgF, AgC104 or AgOTf) resulted in the formation of 2 -deoxydisacchar-ides as anomeric mixtures. Thiem and coworkers reported [507] an efficient activation method for S-(2-deoxyglycosyl)phosphorothioate donors 102 by using N-iodo-succinimide (NIS) or iodonium bis(2,4,6-trimethylpyridine) perchlorate (IDCP) (Scheme 4.94). [Pg.296]

Fig. 46 Reagents and conditions (a) allyl bromide, Sn, CH3CN/H20, ultrasound (b) BnBr, NaH, DMF (c) IDCP, CH2Cl2/MeOH (d) Zn, 95% EtOH, A (e) DMS0/Ac20 (0 03, CH2C12, -78 °C, then Ph3P (g) 9 MHC1, THF (h) NH4HC02, NaCNBH3, MeOH (i) 10% Pd C, MeOH/HCOOH. Fig. 46 Reagents and conditions (a) allyl bromide, Sn, CH3CN/H20, ultrasound (b) BnBr, NaH, DMF (c) IDCP, CH2Cl2/MeOH (d) Zn, 95% EtOH, A (e) DMS0/Ac20 (0 03, CH2C12, -78 °C, then Ph3P (g) 9 MHC1, THF (h) NH4HC02, NaCNBH3, MeOH (i) 10% Pd C, MeOH/HCOOH.
Scheme 5.1 Mechanism of thioglycoside activation (a) by thiophiles X1 such as /V-bromosuccinimicle (NBS), 11,12 methyl triflate,13 dimethyl(methylthio)sulfonium triflate (DMTST),14 phenylselenyl triflate (PhSeOTf),17,18 iV-iodosuccinimide/triflic acid (MS/TfOH),19 20 and iodonium di-sym-collidine perchlorate (IDCP)21 (b) by tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBPA,+)25 and (c) via anomeric sulfoxides.26 The stereochemical outcome of these glycosylations follows the same general trends as with many other glycosyl donor/promoter combinations (m-CPBA = mcta-chloroperbenzoic acid). Scheme 5.1 Mechanism of thioglycoside activation (a) by thiophiles X1 such as /V-bromosuccinimicle (NBS), 11,12 methyl triflate,13 dimethyl(methylthio)sulfonium triflate (DMTST),14 phenylselenyl triflate (PhSeOTf),17,18 iV-iodosuccinimide/triflic acid (MS/TfOH),19 20 and iodonium di-sym-collidine perchlorate (IDCP)21 (b) by tris(4-bromophenyl)ammoniumyl hexachloroantimonate (TBPA,+)25 and (c) via anomeric sulfoxides.26 The stereochemical outcome of these glycosylations follows the same general trends as with many other glycosyl donor/promoter combinations (m-CPBA = mcta-chloroperbenzoic acid).
Scheme 5.7 (a) Mechanism of the w-pentenyl glycoside-based glycosylation method. Electrophiles commonly employed include iodonium di-sym-collidine perchlorate (IDCP) and A-iodosuccinimide/triethylsilyl triflate (NIS/Et3SiOTf) (b) Mechanism for the activation of NIS by EtsSiOTf.55... [Pg.107]

A promoter of intermediate potency is iodonium di-vym-collidinc perchlorate (IDCP), which was successfully used for coupling reactive (armed) NPGs.62 A problem is that some IDCP-promoted reactions tend to stall, leaving substantial amounts of unreacted starting material, an effect probably caused by liberation of collidine during the course of the reaction. [Pg.108]

See other pages where IDCPS is mentioned: [Pg.517]    [Pg.187]    [Pg.191]    [Pg.193]    [Pg.150]    [Pg.32]    [Pg.208]    [Pg.209]    [Pg.219]    [Pg.219]    [Pg.219]    [Pg.312]    [Pg.317]    [Pg.331]    [Pg.332]    [Pg.366]    [Pg.367]    [Pg.372]    [Pg.379]    [Pg.388]    [Pg.388]    [Pg.396]    [Pg.397]    [Pg.408]    [Pg.434]    [Pg.54]    [Pg.100]    [Pg.109]    [Pg.203]    [Pg.204]    [Pg.218]    [Pg.235]    [Pg.135]    [Pg.339]    [Pg.343]    [Pg.343]    [Pg.351]    [Pg.351]    [Pg.66]    [Pg.16]    [Pg.16]   
See also in sourсe #XX -- [ Pg.461 ]



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Iodonium dicollidine perchlorate IDCP)

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