Protecting Groups in Organic Synthesis

To illustrate the purpose and practice of functional group protection, let us suppose that the synthesis of c/.v-2-octene, which we outlined in Section 13-7, has to be adapted for the synthesis of 5-octyn-l-ol. We could write the following  

However, the synthesis as written would fail because the alkyne is a weaker acid than the alcohol (Section 11-8), and the alkynide anion would react much more rapidly with the acidic proton of the alcohol than it would displace bromide ion from carbon  

The hydroxyl group of 4-bromo-l-butanol therefore must be protected before it is allowed to react with the alkynide salt. There are a number of ways to protect hydroxyl groups, but one method, which is simple and effective, relies 

13 Polyfunctional Compounds. Alkadienes. Approaches to Organic Synthesis 

The protected compound is a much weaker acid than the alkyne, and the displacement reaction can be carried out with the alkynide salt without difficulty. To obtain the final product, the protecting group must be removed, and this can be done in dilute aqueous acid solution by an SN1 type of substitution (Sections 8-7D and 8-7E)  

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T.W. Greene P.G.M. Wuts, Protective Groups in Organic Synthesis (2nd edition) J. Wiley Sons, 1991. 

T. W. Greene, Protective Groups in Organic Synthesis, ]ohxi Wiley Sons, Inc., New York, 1988, p. 114. 

Ethers are among the most used protective groups in organic synthesis. They vary from the simplest, most robust, methyl ether to the more elaborate, substituted, trityl ethers developed for use in nucleotide synthesis. They are formed and removed under a wide variety of conditions. Some of the ethers that have been used to protect alcohols are included in Reactivity Chart 1. ... 

Greene, T. W. Wuts, P. G. M. Protective Groups in Organic Synthesis, Second Edition, John Wiley Sons New York, 1991. 

M. Lalonde and T. H. Chan. Use of organosilicon reagents as protective groups in organic synthesis. Synthesis 817 (1985). 

Greene TW, Wuts PGM (1999) Protective groups in organic synthesis. Wiley, New York... 

J. F. W. McOmie, ed., Protective Groups in Organic Synthesis, Plenum Press New York, 1973. 

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