Protecting group chemistry

McOmie, J. F. W. 1973, Protective Groups in Organic Chemistry, Plenum New York... 

In the synthesis of ceftazidime (40) (Fig. 8), the protected, preassembled arninothiazole side chain [68672-66-2] (60) is coupled to a protected 7-ACA first and the C-3 displacement step carried out last. By way of contrast, in the synthesis of ceftriaxone (39) (Fig. 9), the preformed C-3 substituent is introduced onto the cephalosporin nucleus in the first step and then the acyl-amino side chain is introduced. This last step is noteworthy for two reasons in that it demonstrates the use of an activated thio ester in the coupling step and that no protecting group chemistry is requited (192,193). 

A number of standard synthetic reference books are available. A review article by Kossell and Seliger discusses protective groups used in oligonucleotide syntheses, including protection for the phosphate group, which is not included in this book, and a series of articles describe various aspects of protective group chemistry. 

V. Zehavi, Applications of Photosensitive Protecting Groups in Carbohydrate Chemistry, Adv. Carbohydr. Chem. Biochem., 46, 179-204 (1988). 

See also C. B. Reese, Protection of Alcoholic Hydroxyl Groups and Glycol Systems, in Protective Groups in Organic Chemistry, J. F. W. McOmie, Ed., Plenum, New York and London, 1973, pp. 95-143 H. M. Flowers, Protection of the Hydroxyl Group, in The Chemistry of the Hydroxyl Group, S. Patai, Ed., Wiley-Interscience,... 

Protective group chemistry for these amines has been separated from the simple amines because chemically they behave quite differently with respect to protective group cleavage. The increased acidity of these aromatic amines makes it easier to cleave the various amide, carbamate, and sulfonamide groups that are used to protect this class. A similar situation arises in the deprotection of nucleoside bases (e.g., the isobutanamide is cleaved with methanolic ammonia ), again, because of the increased acidity of the NH group. 

Two new sections on the protection for indoles, imidazoles, and pyrroles, and protection for the amide — NH are included. They are separated from the regular amines because their chemical properties are sufficienth different to affect the chemistry of protection and deprotection. The Reactivity Charts in Chapter 8 are identical to those in the first edition. The chart number appears beside the name of each protective group when it is first discussed. 

The search for suitable protecting groups of carbonyl and hydroxyl functions has been of continuous importance in steroid chemistry. As a result of these efforts a good selection of protecting groups is now available for use in organic synthesis. 

The use of biocatalysts for the selective introduction and cleavage of esters is vast and has been extensively reviewed." Therefore only a few examples of the types of transformations that are encountered in this area of protective group chemistry will be illustrated to show some of the basic transformations that have appeared in the literature. The selective... 

A review discusses the condensation of aldehydes and ketones with glycerol to give 1,3-dioxanes and 1,3-dioxolanes. The chemistry of 0 0 and 0 S acetals has been reviewed, and a recent monograph discusses this area of protective groups in a didactic sense. ... 

The use of enamines as protective groups seems largely to be confined to steroid chemistry, where they serve (in their protonated form) to protect the A-B enone system from bromination and reduction. A large body of literature exists on the preparation and chemistry of enamines, which are easily hydrolyzed with water or aqueous acid. 

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