Readily available starting materials

Methanol ethanol and isopropyl alcohol are included among the readily available starting materials commonly found m laboratories where organic synthesis is carried out So too are many other alcohols All alcohols of four carbons or fewer as well as most... 

Not so for synthesis in the chemical industry where a compound must be prepared not only on a large scale but at low cost There is a pronounced bias toward reactants and reagents that are both abundant and inexpensive The oxidizing agent of choice for example in the chemical industry is O2 and extensive research has been devoted to develop mg catalysts for preparing various compounds by air oxidation of readily available starting materials To illustrate air and ethylene are the reactants for the industrial preparation of both acetaldehyde and ethylene oxide Which of the two products is ob tamed depends on the catalyst employed... 

The procedure described here is a large-scale preparation with satisfactory yields of a still very expensive but simple compound from very cheap and readily available starting materials and with ordinary laboratory equipment. This rearrangement of oxaspiropentanes into cyclobutanones appears to be general for the preparation of substituted cyclobutanones. ... 

As an allergen for testing purposes, synthetic 3-pentadecylcatechol is more useful than natural poison ivy extracts (of which it is one component). A stable crystalline solid, it is efficiently prepared in pure form from readily available starting materials. Outline a reasonable synthesis of this compound from 2,3-dimethoxybenzaldehyde and any necessary organic or inorganic reagents. 

The Paal synthesis of thiophenes from 1,4-diketones, 4-ketoaldehydes and 1,4-dialdehydes has found great use in the synthesis of medicinally active compounds, polymers, liquid crystals and other important materials. Furthermore, the discovery of the catalyzed nucleophilic 1,4-conjugate addition of aldehydes, known as the Stetter reaction (Eq. 5.4.1), has enabled widespread use of the Paal thiophene synthesis, by providing 1,4-diketones from readily available starting materials. ... 

The palladium-catalyzed reaction of o-iodoanilides with terminal acetylenic carbinols provides a facile route to the synthesis of quinolines using readily available starting materials (93TL1625). When o-iodoanilide 126 was stirred with acetylenic carbinol 127 in the presence of bis-triphenyl phosphine palladium(ll) chloride in triethylamine at room temperature for 24 h, the substituted alkynol 128 was obtained in 65% yield. On cyclization of 128 with sodium ethoxide in ethanol, 2-substituted quinoline 129 was obtained in excellent yield. 

Woodward achieved his first signal success of a lifetime devoted to the preparation of increasingly complex natural products by total synthesis by the successful preparation of quinine. Despite its elegance, this synthesis did not provide a commercially viable alternative to isolation of the drug from chincona bark. A rather short synthesis for this drug from readily available starting materials has been only recently developed by the group at Hoffmann-LaRoche. (The economics of this synthesis are,... 

The preparation of adamantane from readily available starting materials (Chapter 13, Section I) has opened the door to a study of its many substitution products, both from a chemical and a biological point of view (/). Adamantylamine hydrochloride for example, has been found to exhibit antiviral activity. Presented below are several procedures for the preparation of adamantane derivatives. 

This two step procedure appears to be by far the most convenient one for preparing exo-ch-bicyclo[3 3 0]octane-2-car-boxylic acid from the readily available starting materials The first step of the procedure is also illustrative of the method of obtaining 2-substituted bicyclo[3 3 Ojoctanes4,6 from cis cn-1,5-cyclooctadiene. 

The procedure employs a readily available starting material and produces the pure trans isomer in high yield. The method described is an improvement on that used by Eliel and Rerick2 in that it is not necessary to use a clear solution of lithium aluminum hydride in ether for the preparation of the mixed hydride. It is not necessary to know the precise amount of lithium aluminum hydride used so long as a slight excess is present. The excess hydride is destroyed by adding /-butanol the excess /-butanol has no effect on the subsequent equilibration and purification. The equilibration of the 4 / butylcyclohexanol is effected by adding a small amount of 4-/-butylcyclohexanone. 

The condensation of primary amines with 2,5-dialkoxytetra-hydrofurans to give in one step N-substituted pyrroles is applicable to a variety of substituted aliphatic and aromatic amines.6 The method, largely developed by Clauson-Kaas and associates, has the advantages of simplicity, mild conditions, and generally excellent yields from readily available starting materials. 

Concealed within spirocyclic intermediate 16 are rings B and F of ginkgolide B. Intermediate 16 is readily formed in two steps from a readily available starting material and it contains a strategically placed ketone carbonyl group which provides several options for further advance. A particularly straightforward route to 15 includes the conversion of ketone 16 into enol triflate 21 by means of McMurry s protocol.16 Thus, enolization of 16 with LDA in dimethoxyethane at -78 °C followed by triflation of the enolate oxygen atom with /V-phenyltrifluoromethanesulfonimide furnishes enol triflate 21 in a yield of 80%. 

The developments highlighted in this chapter show that vinylepoxides are readily available starting materials. Several techniques for their regio- and stereoselective synthesis and derivatization exist, and it is consequently to be expected that the use of vinylepoxides as substrates in organic synthesis will increase. 

The present method is a one-step synthesis giving a high yield of 9-chloroanthracene from readily available starting materials. 

This procedure has several advantages over previous methods. It provides a simple direct route to unsymmetrically substituted isoxazoles in which the substituents are unequivocally located. The method uses readily available starting materials and can be used for the synthesis of variety of substituted isoxazoles in which the substituents are nonreactive to butyllithium. Examples of products synthesized by this method7 are given in Table I. 

Look for a combination of substituents present in the TM and in a readily available starting material. 

From Free Radicals RR R"E This last synthetic route, involving the one-electron oxidation of the free radicals RR R"E with an appropriate Lewis acid such as PhjC, is one of the best methods for the extremely fast and clean formation of the element-centered cations RR R"E+. Although this approach requires the presence of the radical species as readily available starting materials, the recent synthesis of stable silyl-substituted radicals of the type (r-Bu2MeSi)3E (E = Si, Ge, Sn) (see Section 2.2.4.1.2) made such an approach a rather attractive and easily accessible synthetic route to the stable and free (r-Bu2MeSi)3E+ cations (Scheme 2.6)... 

Suggest readily available starting materials and reaction conditions suitable for obtaining each of the following compounds by a procedure involving alkylation of a carbon nucleophile. 

The formation of a DPP molecule was first reported in 1974 as a minor product in low yield from the reaction of benzonitrile with ethyl bro-moacetate and zinc. A fascinating study by research chemists at Ciba Geigy into the mechanistic pathways involved in the formation of the molecules led to the development of an efficient one-pot synthetic procedure to yield DPP pigments from readily available starting materials, as illustrated in Scheme 4.10. The reaction involves the treatment of diethyl succinate (1 mol) with an aromatic cyanide (2 mol) in the presence of a strong base. The reaction proceeds through the intermediate 88, which may be isolated and used to synthesise unsymmetrical derivatives. 

Metal-mediated reductive coupling of alkenes and alkynes affords access to complicated organic structures, including carbocyclic and heterocyclic molecules, from readily available starting materials. While most of these coupling reactions were initially developed as stoichiometric processes, many selective, catalytic versions have been developed over the past decade these advancements have made reductive coupling much more attractive to synthetic chemists. 

A classical approach to driving the unfavorable equilibrium of an enzymatic process is to couple it to another, irreversible enzymatic process. Griengl and coworkers have applied this concept to asymmetric synthesis of 1,2-amino alcohols with a threonine aldolase [24] (Figure 6.7). While the equilibrium in threonine aldolase reactions typically does not favor the synthetic direction, and the bond formation leads to nearly equal amounts of two diastereomers, coupling the aldolase reaction with a selective tyrosine decarboxylase leads to irreversible formation of aryl amino alcohols in reasonable enantiomeric excess via a dynamic kinetic asymmetric transformation. A one-pot, two-enzyme asymmetric synthesis of amino alcohols, including noradrenaline and octopamine, from readily available starting materials was developed [25]. 

Fig. 4.6 A relatively simple synthetic route, using readily available starting materials, cyanoacetylene and urea,...

In most cases, pyrazino[l,2- ]pyrazines have been synthesized as highly saturated derivatives with the aim of preparing conformationally restricted compounds which mimic the secondary structure of reverse-turn regions of peptides and proteins. The saturated pyrazino[l,2- ]pyrazine 241 was synthesized from readily available starting materials, the key steps being the preparation of the keto amide 239 and subsequent tandem cyclizations from [6+0] atom fragments (Scheme 42) <20000L301>. 

A straightforward preparation of pyrimidinones and pyrimidinethiones 45 involved reaction of isocyanates or isothiocyanates with the readily available starting material 44, which had previously been described by the same authors. A particularly interesting application was the use of sugar isothiocyanates to give nucleosides. Nucleophilic displacements of the sulfur groups in the products were also reported <06EJO634>. 

In a detailed investigation, Turner and coworkers have described the preparation and application of solid-supported cyclohexane-1,3-dione as a so-called capture and release reagent for amide synthesis, as well as its use as a novel scavenger resin [125]. Their report included a three-step synthesis of polymer-bound cyclohexane-1,3-dione (CHD resin, Scheme 7.104) from inexpensive and readily available starting materials. The key step in this reaction was microwave-assisted complete hydrolysis of 3-methoxy-cyclohexen-l-one resin to the desired CHD resin. 

---