将下面文章翻译成汉语

将下面文章翻译成汉语Broad mechanistic insight is crucial to synthetic analysis. The relative position of functional groups in a potential reactant may lead to special reactions. Mechanistic concepts are also the basis for developing new reactions that may be necessary in a particular situation. In this chapter, tactical tools of synthesis such as protective groups and synthetic equivalent groups have been considered. The objective of synthetic analysis and planning is to develop a reaction sequence that will efficiently complete the desired synthesis within the constraints which apply.The planning of a synthesis involves a critical comparative evaluation of alternative reaction sequences that could reasonably be expected to lead the desired structure from appropriate starting materials. In general, the complexity of any synthetic plan will increase with the size of the molecule and with increasing numbers of functional groups and chiral centers. The goal of synthetic analysis is to recognize possible pathways to the target compound and to develop a suitable sequence of synthetic steps.The restrictions which apply to a synthesis will depend on the reason the synthesis is being conducted. A synthesis of a material to be prepared in substantial quantity may impose a limitation as to cost of starting materials. Synthesis for commercial products must meet such criteria as economic feasibility, acceptability of by-products, and safety. Synthesis of complex structures with several chiral centers must deal with the problem of stereoselectivity. If an enantiomerically pure material is to be synthesized, the means of controlling enantioselectivity must be considered. The development of a satisfactory plan is the intellectual challenge to the chemists. The task puts a premium on creativity and ingenuity. There is no single correct solution. While there is no established routine by which a synthetic plan can be formulated, general principles that should guide synthetic analysis and planning have been described.The initial step in creating a synthetic plan should involve a retrosynthetic analysis. The structure of the molecular is discussed step by step along reasonable pathways to successively simpler compounds until molecules that are acceptable starting materials are reached. Several factors enter into this process, and all are closely interrelated. The recognition of bond disconnections allows the molecules to be broken down into key intermediates. Such disconnection must be made in such a way that it is feasible to form the bonds by some synthetic process. Thus, the relative placement of potential functionality will strongly influence which bond disconnection are preferred. To emphasize that these bond disconnections must correspond to transformation that can be conducted in the synthetic sense, they are sometimes called antisynthetic transforms, that is, the reverse of synthetic steps. The overall synthetic plan will consist of a sequence of reactions designed to construct the total molecular framework from the intermediates. The plan should take into account the advantages of a convergent synthesis. The objective of making a synthesis convergent is to decrease its overall length. In general, it is desirable to construct the molecule from a few key fragments that can be combined late in the synthesis rather than to build the molecule step by step from a single starting material. The reason for this is that the overall yield is the multiplication product of the yields for all the individual steps. Overall yields will decrease as the number of steps to which the original starting materials is subjected increase.After a plan for assembly of the key intermediates into the molecular framework has been developed, the details of incorporation and transformation of functional groups must be considered. It is frequently necessary to interconvert functional groups. This may be to develop a particular kind of reactivity at a center or to avoid interference with a particular reaction step. Protective groups and synthetic equivalent groups are important for planning of functional group transformations. Achieving the final array of functionality is often less difficult than establishing the overall molecular skeleton and stereochemistry, because of the large number of procedures which exist for interconverting the common functional groups.。