Retrosynthetic analysis synthesis

The importance of biotin in nutrition and increasing commercial needs combine to suggest the need for short and economical synthesis. Retrosynthetic analysis using cysteine as SM goal suggested a number of synthetic pathways for study, one of which has been demonstrated as shown below. 

Organic synthesis is stressed throughout this book, with progressive discussions of the process involved in developing a synthesis. Retrosynthetic analysis is emphasized, and the student learns to work backward from the target compound and forward from the starting materials to find a common intermediate. 

Introduction to Organic Chemical Synthesis Retrosynthetic Analysis... 

To recognize the different levels of representation of biochemical reactions To understand metabolic reaction networks To know the principles of retrosynthetic analysis To understand the disconnection approach To become familiar with synthesis design systems... 

The aim of a retrosynthetic analysis is the transformation of a synthesis target into progressively simpler structures, following a pathway to commercially available starting materials. 

Tran orm-based or long-range strategies The retrosynthetic analysis is directed toward the application of powerful synthesis transforms. Functional groups are introduced into the target compound in order to establish the retion of a certain goal transform (e.g., the transform for the Diels-Alder reaction, Robinson annulation, Birch reduction, halolactonization, etc.). 

The retrosynthetic analysis is performed in two steps in a first step, SYNGEN dissects the skeleton to find all fully convergent bondsets which utili2e starting material skeletons found in two successive levels of cuts. A bondset is a set of skeletal bonds that is cut during the retrosynthetic analysis or formed in any given synthesis. 

The Japanese program system AlPHOS is developed by Funatsu s group at Toyo-hashi Institute of Technology [40]. AlPHOS is an interactive system which performs the retrosynthetic analysis in a stepwise manner, determining at each step the synthesis precursors from the molecules of the preceding step. AlPHOS tries to combine the merits of a knowledge-based approach with those of a logic-centered approach. 

The retrosynthetic analysis of a target compound is a systematic approach in developing a synthesis plan starting with the target structure and working backward to available starting materials. 

In the last fifteen years macrolides have been the major target molecules for complex stereoselective total syntheses. This choice has been made independently by R.B. Woodward and E.J. Corey in Harvard, and has been followed by many famous fellow Americans, e.g., G. Stork, K.C. Nicolaou, S. Masamune, C.H. Heathcock, and S.L. Schreiber, to name only a few. There is also no other class of compounds which is so suitable for retrosynthetic analysis and for the application of modem synthetic reactions, such as Sharpless epoxidation, Noyori hydrogenation, and stereoselective alkylation and aldol reactions. We have chosen a classical synthesis by E.J. Corey and two recent syntheses by A.R. Chamberlin and S.L. Schreiber as examples. 

When planning the synthesis of a compound using an organometallic reagent or indeed any synthesis the best approach is to reason backward from the product This method is called retrosynthetic analysis Retro synthetic analysis of 1 methylcyclohexanol suggests it can be prepared by the reaction of methylmagnesmm bromide and cyclohexanone... 

On the basis of this retrosynthetic analysis design a synthesis of N methyl 4 phenylpipendine (compound A where R = CH3 R = C6H5) Present your answer as a series of equations show ing all necessary reagents and isolated intermediates... 

Methodology for the enantioselective synthesis of a broad range of chiral starting materials, by both chiral catalytic and controller-directed processes, is rapidly becoming an important factor in synthesis. The varied collection of molecules which are accessible by this technology provides another type of chiral S-goal for retrosynthetic analysis. 

Antithetic Analysis. (Synonymous with Retrosynthetic Analysis) A problem-solving technique for transforming the structure of a synthetic target molecule to a sequence of progressively simpler structures along a pathway which ultimately leads to simple or commercially available starting materials for a chemical synthesis. 

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. 

Target Molecule. (TGT) A molecule whose synthesis is under examination by retrosynthetic analysis. 

Methoxatin, now known as coenzyme PQQ, was originally obtained from methylotrophic bacteria but is now known to be a mammalian cofactor, for example, for lysyl oxidase and dopamine p-hydroxylase. The first synthesis of this rare compound was accomplished by the route outlined below. In the retrosynthetic analysis both of the heterocyclic rings were disconnected using directly keyed transforms. 

The retrosynthetic analysis of fumagillol, the alcohol from which the antibiotic fumagillin is derived, has been outlined in Section 2.3. The experimentally demonstrated synthesis of fumagillol was derived by T-goal directed search to apply the Diels-Alder transform. 

Retrosynthetic analysis of antheridic acid produced a totally different plan of synthesis from that which had been employed for the structurally related target gibberellic acid. The synthesis of antheridic acid, which included a number of novel steps, allowed definitive assignment of structure and revised stereochemistry at C(3). 

The multistrategic retrosynthetic analysis of retigeranic acid, which led to the synthesis outlined below, has been described in Section 6.6 of Part One. 

Despite the structural relationship between ginkgolide B and bilobalide, retrosynthetic analysis of the latter produced a totally different collection of sequences. A successful synthesis of bilobalide was implemented using a plan which depended on stereochemical and FG-based strategies. A process for enantioselective synthesis was based on an initial enantioselective Diels-Alder step in combination with a novel annulation method. 

Venustatriol, a marine-derived antiviral agent, as with many polyether structures, is a straightforward problem for retrosynthetic analysis. The major issues, clearance of stereocenters and topologically strategic disconnection, were readily resolved to generate the pathway of synthesis described below. 

Scheme 1 outlines the retrosynthetic analysis of the Woodward-Eschenmoser A-B variant of the vitamin B12 (1) synthesis. The analysis begins with cobyric acid (4) because it was demonstrated in 1960 that this compound can be smoothly converted to vitamin B12.5 In two exploratory corrin model syntheses to both approaches to the synthesis of cobyric acid,6 the ability of secocorrinoid structures (e. g. 5) to bind metal atoms was found to be central to the success of the macrocyclization reaction to give intact corrinoid structures. In the Woodward-Eschenmoser synthesis of cobyric acid, the cobalt atom situated in the center of intermediate 5 organizes the structure of the secocorrin, and promotes the cyclization... 

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