Retrosynthetic analysis for

The key features of Curran s productive and elegant tandem radical cyclization strategy are illustrated in a retrosynthetic analysis for hirsutene (1) (see Scheme 27). The final synthetic event was projected to be an intermolecular transfer of a hydrogen atom from tri-rc-butyltin hydride to the transitory tricyclic vinyl radical 131. The latter can then be traced to bicyclic tertiary radical 132 and thence to monocyclic primary radical 133 through successive hex-5-enyl-like radical cyclizations. It was anticipated that the initial radical 133 could be generated through the abstraction of the iodine atom from... 

Much of the recent work on the use of anodic amide oxidation reactions has focused on the utility of these reactions for functionalizing amino acids and for synthesizing peptide mimetics [13]. For example, in work related to the cyclization strategy outlined in Scheme 3, the anodic amide oxidation reaction has been used to construct a pair of angiotensin-converting enzyme inhibitors [14]. The retrosynthetic analysis for this route is outlined in Scheme 4. In this work, the anodic oxidation reaction was used to functionalize either a proline or a pipercolic add derivative and then the resulting methoxylated amide used to construct the bicyclic core of the desired inhibitor. A similar approach has recently been utilized to construct 6,5-bicyclic lactam building blocks for... 

Perform a retrosynthetic analysis for each of the following molecules. Develop at least three outline schemes. Discuss the relative merits of the three schemes, and develop a fully elaborated synthetic plan for the one you consider to be most promising. 

Moreover the following retrosynthetic analysis for the preparation of K is not valid either because there is no good reaction to directly convert an olefin to a ketone ... 

Notwithstanding the analogy offered by Scheme 2, these considerations were nevertheless regarded as being risky. The capacity to invert configuration at C9 by a more reliable chemical means was incorporated into our retrosynthetic analysis for this... 

Our retrosynthetic analysis for lipid I is presented below [Scheme 2], Our protected version of lipid I employed acetate protective groups for the carbohydrate hydroxyls, methyl esters for each of the carboxyl groups in the pentapeptide side chain, and trifluoroacetate for the terminal amino group of the lysine residue. These base-cleavable protective groups could be removed in a single operation in the final step of our synthesis and would not subject the sensitive diphosphate linkage to acidic reagents or reaction conditions. 

A retrosynthetic analysis for the alkene R R2C=CH R3 shows two possible carbonyl compounds as starting materials. 

A retrosynthetic analysis for a target molecule of either a primary or secondary amine is therefore a two-stage process first an FGI to reveal an imine, and then a disconnection to ammonia (or primary amine) and the carbonyl compound. 

This reaction is used as one step [(7) to (6)] of the multistage synthesis of the monocyclic sesquiterpenic hydrocarbon, dehydro-a-curumene (3) [6-methyl-2-(4-methylphenyl)hepta-l,5-diene].247 The overall strategy is revealed from a retrosynthetic analysis for this compound, and is of interest since it emphasises the logic of the disconnection approach and draws together a number of important reactions which are relevant to this discussion of unsaturated compounds. 

A retrosynthetic analysis for this latter compound (as shown below) shows that it could arise from ethylene oxide [reagent equivalent to (5), see Section 5.4.2, p. 533], and ethyl acetoacetate [reagent equivalent to (6), see Section 5.8.5, p. 619],... 

A similar retrosynthetic analysis for 5-ethyl-5-phenylbarbituric acid (94) discloses urea and diethyl ethylphenylmalonate. 

In a reaction which is mechanistically related to the Skraup reaction an a,/ -unsaturated carbonyl compound, generated by way of an acid-catalysed aldol condensation, reacts with a primary aromatic amine in the presence of acid to yield a quinoline derivative (Doebner-Miller reaction). For example, when aniline is heated with paraldehyde (which depolymerises to acetaldehyde during the reaction) in the presence of hydrochloric acid the final product is 2-methyl-quinoline (101) (quinaldine, Expt 8.40). Retrosynthetic analysis for the 1,2-dihydroquinoline reveals crotonaldedhyde as the unsaturated carbonyl component which is in turn formed from acetaldehyde (see Section 5.18.2, p. 799). 

The starting materials for the synthesis of 2-phenylquinoline-4-carboxylic acid (Expt 8.41) may be discovered by a similar retrosynthetic analysis for the 1,2-dihydro derivative. 

A retrosynthetic analysis for 2,4,6-trimethylquinoline (102) reveals p-toluidine and pentane-2,4-dione. This is an example of the Combes reaction. 

Retrosynthetic analysis for 6-methylisoquinoline (104) reveals p-tolu-aldehyde and a-aminoacetaldehyde. 

A retrosynthetic analysis for coumarin reveals salicylaldehyde and acetic anhydride (under basic conditions) as suitable reagent equivalents of the derived synthons. 

A retrosynthetic analysis for flavone (118) reveals o-benzoyloxyacetophe-none (122), readily formed by the benzoylation of o-hydroxyacetophenone. 

Retrosynthetic Analysis. For each of the following syntheses show (1) your retrosynthetic analysis and (2) all reagents and reaction conditions required to transform a commercially available starting material to the target molecule. 

Retrosynthetic analysis for the synthesis of a key building blockl for such a glycopeptide mimics is shown in Figure 10. It was envisaged that the synthesis of I could be achieved by a coupling reaction of the glycosyl isocyanates II and the amino acid derivatives III, and initial work focused on the synthesis of the glycosyl isocyanates IV. 

Figure 10. Retrosynthetic analysis for the glycopeptide mimics with urea-giycosyi bonds...

The initial retrosynthetic analysis for a route to travoprost, using the Newton-Roberts route, provided three key synthons a) the a-chain was derived from the commercially available Wittig salt, (4-carboxybutyl)triphenylphosphonium bromide b) the co-chain required a route to the single enantiomer mixed cuprate reagent, most conveniently derived from the propargylic alcohol via the trans-vinyl iodide, to be developed and c) the cyclopentane core could be derived from the single enantiomer protected bromohydrin (Figure 30.3).llc 25... 

A basic retrosynthetic analysis for our planned approaches is illustrated in Scheme 11. 

Scheme 10.1 Fraser-Reid s retrosynthetic analysis for (—)-silphiperfolene.

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