Synthesis retrosynthetic tree

Each reference discusses a proposed biosynthetic pathway for the molecule shown. Construct a retrosynthetic tree based on that pathway and then show the total synthesis. 

There are a number of computer programs which can assist the synthetic chemist in the retrosynthetic analysis of a target compound. One that is specifically designed to be applied to the synthesis of chiral compounds is the CHIRON program, developed at the University of Montreal by Professor Steve Hanessian. CHIRON does not generate a full retrosynthetic tree but rather yields readily available starting materials from the Chiral Poof that contain the chirality needed to construct the product in optically pure form. 

Ex-Target Tree. (EXTGT Tree) A branching tree structure formed by retrosynthetic analysis of a target molecule (treetop). Such trees grow out from a target and consist of nodes which correspond to the structures of intermediates along a pathway of synthesis. 

The computer-assisted synthetic analysis designated OCSS (organic chemical simulation of synthesis) and LHASA (logic and heuristics applied to synthetic analysis) were designed to assist chemists in synthetic analysis by Corey et LHASA generates trees of synthetic intermediates from a target molecule by analysis in the retrosynthetic direction. 

SYNLMA, an expert system for organic synthesis, with a theorem prover as its inference engine and NCI s XTCHEM as its user interface, uses a retrosynthetic approach to find reaction pathways and generate a problem-solving tree representing the alternative designs it has explored. 

Probably the least mechanical and easily defined operation is the initial choice of bondsets as a starting point for the protocol. Criteria for bond selection on grounds of both target functionality and target skeleton are applied but the procedure is still somewhat arbitrary and in need of sharper definition. In view of the enormous size of the synthesis tree this is probably inevitable, but it may be noted that it is no more arbitrary than the traditional description of stepwise retrosynthetic development from target functionality. In that procedure a bondset is also ultimately defined in steps, of course, by the constructions selected from the functionality each time. Such a procedure in fact misses many... 

The logic centered approach leads to a restricted set of structures that may be converted in a single step to the target. Each new structure can. in turn, be converted to a new structure. The purpose of the retrosynthetic analysis is to generate synthetic intermediates (the synthesis tree) that terminate with a number of starting materials.Corey et al. outlined this approach in 1964 in his synthesis of longifolene (73), which is shown in Scheme 10.4.- 2 This synthesis used the 33 ieland-Miescher ketone (72) as the starting material. - Analyses... 

From the preceding discussions it is clear that there are many approaches for a di.sconnection approach that focuses upon construction of a synthesis tree. Corey et al. described five different strategies for retrosynthetic analysis ... 

A typical example of an information-based retrosynthetic system is LHASA. This system generates a synthesis tree utilising a system of transforms which describe individual steps to construct a target. 

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