Protective group strategies

A highlight in the application of RCM methodology in natural product synthesis is Hirama s total synthesis of ciguatoxin CTX3C (183) [90], including the more recent improved protective group strategy, as depicted in Scheme 34 [90b]. The structure of 183 spans more than 3 nm and is characterized by 12 six- to nine-membered trans-fused cyclic ethers and a spiroannulated terminal tetra-... 

In each of the synthetic transformations shown, the reagents are appropriate for the desired transformation but the reaction would not succeed as written. Suggest a protective group strategy that would permit each transformation to be carried out to give the desired product. 

Fig. 4.2 Problematic functional groups (inset) and protecting group strategy to alleviate problems caused by the harsh cycloaddition conditions...

The regioselective alkylation and acylation of 3,5-diamino-l,2,4-triazole 19 using a simple protecting group strategy has been described in detail <2006RJA624, 2006ZPK632>. 

Aloc-protecting group strategy. Utilizing this pathway a number of N-Ras derivatives containing natural and non-natural lipid residues were produced and the technique was extended also allowing the synthesis of fluorescent derivatives. 

New Synthetic Methods Emphasizing Deoxyfluoro Sugars and Protective-Group Strategy... 

Because of the polyfunctional nature of carbohydrates, protective-group strategy plays an important role in synthetic methodology involving this class of compounds. In the present Chapter, results are described from a study of the utility of N-trimethylsilyl- and N-tert-butyldimethylsilyl-phthalimide for the selective silylation of primary hydroxyl groups in carbohydrates. Also described, is a new, facile method for cleavage of acetals and dithioacetals in carbohydrate derivatives the method involves treatment of the derivatives with a dilute solution of iodine in methanol. 

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