What is synthesis

Synthesis is a process by which we can convert a simple compound A to a more complicated compound B. For that purpose we must employ an appropriate chemical reaction C. Synthesis is therefore a function involving the three parameters A, B, and C. There are three kinds of synthetic studies. 

Of course there is another type of synthesis. That is synthesis of any kinds of target molecules from any kinds of starting materials to generate compounds with the desired physical or biological properties. This is the way popular in materials science and medicinal chemistry. 

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If the yield of each step is again 90%, what is the overall yield of this five step convergent synthesis ... 

The y-lactone problem is made easier because the FGs are all based on oxygen. The molecule can therefore be disconnected without FGl except for oxidation or reduction. Let s now look at the synthesis of a molecule with a difficult FG the muscle relaxant baclofen TM 349. What is the difficult FG ... 

An important concern to chemists is synthesis the challenge of preparing a particular compound m an economical way with confidence that the method chosen will lead to the desired structure In this section we will introduce the topic of synthesis emphasiz mg the need for systematic planning to decide what is the best sequence of steps to con vert a specified sfarfmg mafenal fo a desired producf (fhe target molecule)... 

Sorbitol is a sweetener often substituted for cane sugar because it is better tolerated by dia betics It IS also an intermediate in the commercial synthesis of vitamin C Sorbitol is prepared by high pressure hydrogenation of glucose over a nickel catalyst What is the structure (including stereochemistry) of sorbitoP... 

Methamphetannne is a notorious street drug One synthesis involves reductive amination of benzyl methyl ketone with methylamine What is the structure of methamphetamine ... 

A synthesis of the analgesic substance phenacetm is outlined in the following equation What IS the structure of phenacetm ... 

The mixture of carbon monoxide and hydrogen is enriched with hydrogen from the water gas catalytic (Bosch) process, ie, water gas shift reaction, and passed over a cobalt—thoria catalyst to form straight-chain, ie, linear, paraffins, olefins, and alcohols in what is known as the Fisher-Tropsch synthesis. 

Many human diseases are caused when certain proteins are either over- or underexpressed. Eor example, breast cancer can be induced by overexpressing certain cellular oncogenes within mammary tissue. To study the disease, researchers produce a line of transgenic mice that synthesize an abnormal amount of the same protein. This leads to symptoms of the disease in mice that are similar to what is found in humans. A protein can be overexpressed by inserting a DNA constmct with a strong promotor. Conversely, underexpression of a protein can be achieved by inserting a DNA constmct that makes antisense RNA. This latter blocks protein synthesis because the antisense RNA binds and inactivates the sense mRNA that codes for the protein. Once a line of mice is developed, treatments are studied in mice before these therapies are appHed to humans. 

Four different material probes were used to characterize the shock-treated and shock-synthesized products. Of these, magnetization provided the most sensitive measure of yield, while x-ray diffraction provided the most explicit structural data. Mossbauer spectroscopy provided direct critical atomic level data, whereas transmission electron microscopy provided key information on shock-modified, but unreacted reactant mixtures. The results of determinations of product yield and identification of product are summarized in Fig. 8.2. What is shown in the figure is the location of pressure, mean-bulk temperature locations at which synthesis experiments were carried out. Beside each point are the measures of product yield as determined from the three probes. The yields vary from 1% to 75 % depending on the shock conditions. From a structural point of view a surprising result is that the product composition is apparently not changed with various shock conditions. The same product is apparently obtained under all conditions only the yield is changed. 

What is the cost of ATP-ADP exchange relative to the energy cost of ATP synthesis itselD We already noted that moving 1 ATP out and 1 ADP in is the equivalent of one proton moving from the cytosol to the matrix. Synthesis of an... 

Under these conditions, what is the maximum ratio of [ATP]/[ADP] attainable by oxidative phosphorylation when [PJ = 1 mM (Assume AG° for ATP synthesis = +30.5 kj/mol.)... 

Assuming that the concentrations of ATP, ADP, and P in chloroplasts are 3 mM, 0.1 mM, and 10 mM, respectively, what is the AG for ATP synthesis under these conditions Photosynthetic electron transport establishes the proton-motive force driving photophosphorylation. What redox potential difference is necessary to achieve ATP synthesis under the foregoing conditions, assuming an electron pair is transferred per molecule of ATP generated ... 

If noncyclic photosynthetic electron transport leads to the translocation of 3 H /e and cyclic photosynthetic electron transport leads to the translocation of 2 H /A, what is the relative photosynthetic efficiency of ATP synthesis (expressed as the number of photons absorbed per ATP synthesized) for noncyclic versus cyclic photophosphorylation (Assume that the CFiCEq ATP synthase yields 1 ATP/3 H. )... 

Ono and Lash have been the two pioneers in applying the BZ reaction to the synthesis of pyrroles and, particularly, with applications to the synthesis of novel fused and other porphyrins. Although the concept was recognized by Barton and Zard, Ono and Lash independently discovered the conversion of 2-pyrrolecarbo ylates, prepared by the BZ reaction, into porphyrins by what is now a standard protocol (1. LiAlfL 2. 3. 

The sex attractant given off by the common housefly is an alkene named muscahtre. Propose a synthesis of muscalure starting from acetylene and any alkyl halides needed. What is the IUPAC name for muscalure ... 

A chemist requires a large amount of l-bromo-2-pentene as starting material for a synthesis and decides to carry out an NBS allylic broinination reaction. What is wrong with the following synthesis plan What side products would form in addition to the desired product ... 

During our previous discussion of strategies for working synthesis problems in Section 8.9, we said that ids usually best to work a problem backward, or retrosyntheticnlly. Look at the target molecule and ask yourself, "What is an immediate precursor of this compound " Choose a likely answer and continue working backward, one step at a time, until you arrive at a simple starting material. Let s try some examples. 

Problem 16.24 In planning a synthesis, it s as important to know what not to do as to know what to do. As whiten, the following reaction schemes have flaws in them. What is wrong with each ... 

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