Troc group

Cd, AcOH. These conditions were reported to be superior to the use of Zn/AcOH. The authors also reported that the Troc group is not stable to hydrogenation with Pd-C (TsOH, DMF, H2), but is stable to hydrogenation... 

The Troc group on tryptophan is stable to CF3COOH, CF3SO3H, and H2 Pd, but can be cleaved with 0.01 M NaOH/MeOH, hydrazine/Me0H/H20, Cd/AcOH/DMF. Cleavage with Zn/AcOH is only partially complete. 

Removal of Troc Group /V -(Fluoren-9-ylmethoxycarbonyl)-Thr[0-(3,4,6-tri-0-acetyl-2-deoxy-2-acet-amido-P-D-glucopyranosyl)]-OPfp (95) [3441... 

The Troc group has a weaker neighbor group effect than the acetyl group. (Ether protected trichloroacetimidates are more reactive than... 

What is the mechanism involved in the deprotection of the Troc group ... 

An excerpt of a synthesis of the potent antitumour agent FR-900482 [Scheme 3.126] illustrates the use of an N, O-acetal with additional Af-protection in the form of a 2,2,2-trichloroethoxycarbonyl (TVoc) group (see section 8.3.7) in a multifunctional environment.244 245 The A 0-acetal survived the mildly acidic conditions required to deprotect the p-methoxybenzyl group that preceded the formation of the triflate 1263. Later, reductive cleavage of the Troc group and simultaneous hydrolysis of the oxazolidine ring was accomplished in a single... 

The Troc group played an important role in Boger s synthesis of Teichopla-nin.243 Considerable effort was expended in optimising the conditions for its removal An example is the deprotection shown in Scheme 8.109. Various metals were used as reductants such as zinc, cadmium and cadmium-lead couple, but the best results (80% yield) were obtained using zinc-lead couple in M aqueous ammonium acetate in THF at room temperature. Zinc-lead couple is easily prepared. Yellow lead oxide is dissolved in warm aqueous acetic acid (1 1) and the solution added to a vigorously stirred suspension of zinc dust in deionised water. The zinc darkens as lead deposits on its surface, and forms clumps that... 

A number of more esoteric methods have been devised for the reductive cleavage of Troc groups, which the synthetic community have been reluctant to adopt. These include cobalt(l) phthalocyanine25 and sodium 2-thiophenetellur-olate,2S9 which is readily obtained in a catalytic cycle by the sodium borohy-dride reduction of commercially available bis(2-thienyl)ditellurid. Electrolysis is a method that might be considered in special cases.260... 

By way of contrast, the Lability of the oxazolidine N, 0-acetal group is markedly enhanced by first removing the electron withdrawing carbamate group. For example. in the synthesis of FR-900482 [Scheme 8.158], Terashima and co-workers284 excised a Troc group by reductive elimination with zinc in aqueous acetic... 

Trichloroethyl chloroformate was initially used as a reagent for the introduction of the Troc group (Scheme However, there are several drawbacks to this reagent rather... 

The Troc group is not stable towards hydrogenation over Pd/C catalyst, but is stable to hydrogenations with Ru/C or Pt/C as catalysts. 

Similarly to the Aloe protection, the Troc group is mainly used for specific synthetic purposes where acidic or basic deprotection steps are avoided as encountered in the synthesis of glycopeptidesP (see Section 6.3). 

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