TCBoc protective group

The chloroformate of the tertiary alcohol l,l,l-trichloro-2-methylpropan-2-ol 90, 2,2,2-trichloro-tert-butyl chloroformate 91 (TCBoc-Cl), is a reagent that can be used to introduce the TCBoc protective group, and is stable under acidic and basic con-... 

Protection of amino groups. Amino acids are converted to TCBpC-protected amino acids by reaction with 1 under the usual Schotten-Baumann conditions (80-95 7o yield). The products are nicely crystalline and are readily soluble in organic solvents. The TCBOC group is stable to N NaOH (40°, 2 hours) and to TFA (20°, 2 hours). The protecting group can be cleaved, as expected, with zinc in acetic acid or by reaction with lithium cobalt(I)-phthalocyanine. 

The Trichloro-tert.-butoxy-carbonyl (TCBOC) group survives the cleavage conditions of most other protective groups, and is cleaved under very mild conditions by PcCo a reagent that does not affect the other customary blocking groups (ref. 6). 

The use of TCB as the phosphite/phosphate protection and of TCBOC for the protection of the exocyclic amino functions of the bases enables an uniform deprotection strategy. Nevertheless care is necessary a study of the influence of the electron withdrawing properties of guanosine 2-N-protecting groups on the stability of guanosine revealed relative de-stabilisation by TCBOC vs. p-tert.-butyl benzoyl. 

A new protecting group, 2,2,2-trichloro-tert-butyloxycarbonyl (TCBOC) has been employed to protect the imido unit of uracil in a synthesis of 2 -0-methyluridine (Scheme 4), the group being selectively removed using zinc in pentan-2,4-dione/pyridine. ... 

X.X. Zhou, I. Ugi and J. Chattopadhyaya, A Convenient Preparation of N-protected Nucleosides with the 2,2,2-Trichloro-terrt-butyloxycarbonyl (TCBOC) Group. Structural Assignment of N,N-bis-TCBOC-Guanosine and its Deoxy Analogue, Acta Chem. Scand, B39 (1985) 761-765. 

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