Uses in Organic Synthesis

Ketones are selectively reduced to alcohols using Ph2SbH and AlClg esters, acid chlorides, alkyl halides or alkenes are unaffected. 

Wolfsberger, Chem. Ztg. 1985, 109, 53. Review on addition of As-H and Sb-H bonds to alkenes and alkynes. 

Tetrahedron Lett., 1985, 26, 6447. Reaction of Ph3AsCH2CHO, Br with RCHO. 

Liu and T. Lu, Wuhan Daxue Xuebao Ziran Kexueban, 

195962. Reactions of Ph-As=CHCO Me with o-HO-aryl-COR.  

Wuli Huaxue Xuebao, 1985, 6. Photolysis of Ph M. 

Vinh and B. Munson, Org. Mass. Spectrom., 1986, 41, Proton affinities 

Geoffroy, A. Ulnares, and S.P. Mishra, J. Chem. Soc., Faraday Trana. 1. 

Gamayurova, N.A. Nlyazov,and F.G. Khalltov, Zh. Obshch. Khlm.. 1985, 55, 2493. Reaction of Ph3AsO and H02C(CH2)j C02H. 

Pandey and R.C. Smivastava, Synth. React. Inorg. Met- Org.,Chem.. 1985, 

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Some systematic studies on the different reaction schemes and how they are realized in organic reactions were performed some time ago [18]. Reactions used in organic synthesis were analyzed thoroughly in order to identify which reaction schemes occur. The analysis was restricted to reactions that shift electrons in pairs, as either a bonding or a free electron pair. Thus, only polar or heteiolytic and concerted reactions were considered. However, it must be emphasized that the reaction schemes list only the overall change in the distribution of bonds and ftee electron pairs, and make no specific statements on a reaction mechanism. Thus, reactions that proceed mechanistically through homolysis might be included in the overall reaction scheme. 

The standard redox potentials of inorganic oxidants used in organic synthesis are generally around or above + 1.0 V. Organic substrates do not have such high potentials. The values for the CH4/CH3OH and CjHj/CjHjOH couples are at +0,59 V and 0.52 V, respectively. The oxidation of alcohols and aldehydes corresponds to values around 0.0 V (W.M. 

Palladium Compounds, Complexes, and Ligands Widely Used in Organic Synthesis... 

Mercuric Nitrate. Mercuric nitrate [10045-94-0] Hg(N02)2, is a colorless dehquescent crystalline compound prepared by the exothermic dissolution of mercury in hot, concentrated nitric acid. The reaction is complete when a cloud of mercurous chloride is not formed when the solution is treated with sodium chloride solution. The product crystallizes upon cooling. Mercuric nitrate is used in organic synthesis as the starting material and for the formulation of a great many other mercuric products. 

Properties of zinc salts of inorganic and organic salts are Hsted in Table 1 with other commercially important zinc chemicals. In the dithiocarbamates, 2-mercaptobenzothiazole, and formaldehyde sulfoxylate, zinc is covalendy bound to sulfur. In compounds such as the oxide, borate, and sihcate, the covalent bonds with oxygen are very stable. Zinc—carbon bonds occur in diorganozinc compounds, eg, diethjizinc [557-20-0]. Such compounds were much used in organic synthesis prior to the development of the more convenient Grignard route (see Grignard reactions). 

Borane complexes are the most widely used commercial boron compounds, after sodium borobydride. Examples used in organic synthesis are amine borane complexes and borane complexes of tetrahydrofuran and dimethyl sulfide. 

Monochloramine is also used in organic synthesis for preparation of amines, substituted hydrazines, etc. For example, reaction of NH2CI with 3-azabicyclo [3.3.0]octane [5661-03-0] yields A/-amino-3-azabicyclo[3.3.0]octane [54528-00-6] a pharmaceutical intermediate (38). 

Sodium ethoxide is used in organic synthesis as a condensing and reducing agent. The reaction between sodium ethoxide and sulfur monochloride yields diethyl thiosulfite (19). 

In recent years there has been a proliferation of new reactions and reagents that have been so useful in organic synthesis that often people refer to them by name. Many of these are stereoselective or regioselecth/e methods. While the expert may know exactly what the Makosza vicarious nucleophilic substitution, or the Meyers asymmetric synthesis refers to, many students as well as researchers would appreciate guidance regarding such "Name Reactions". 

The search for suitable protecting groups of carbonyl and hydroxyl functions has been of continuous importance in steroid chemistry. As a result of these efforts a good selection of protecting groups is now available for use in organic synthesis. 

Because enolate anions ffle sources of nucleophilic car bon, one potential use in organic synthesis is their- reaction with alkyl halides to give a-alkyl derivatives of aldehydes and ketones ... 

The reaction of ozone with an aromatic compound is considerably slower than the reaction with an alkene. Complete ozonolysis of one mole of benzene with workup under non-oxidative conditions will yield three moles of glyoxal. The selective ozonolysis of particular bonds in appropriate aromatic compounds is used in organic synthesis, for example in the synthesis of a substituted biphenyl 8 from phenanthrene 7 ... 

Although the Paterno-Buchi reaction is of high synthetic potential, its use in organic synthesis is still not far developed. In recent years some promising applications in the synthesis of natural products have been reported. The scarce application in synthesis may be due to the non-selective formation of isomeric products that can be difficult to separate—e.g. 6 and 7—as well as to the formation of products by competitive side-reactions such as Norrish type-I- and type-II fragmentations. 

Although the base-catalyzed addition of nitroalkanes to electron-deficient olefins has been extensively used in organic synthesis fsee Michael addition Chapter 4, it is only recently that the reaction has been extended to the cyclopropanadon reaction. In 1978, it was reported that the anion of nitromethane reacts with certain highly electron-deficient olefins to produce cycloptopanesingoodyieldrEq. 7.36. More recently, this reaction has been extended to more general cyclopropanadons, as shown in Eqs. 7.37 and 7.38, in which potassittm salts of nitroalkanes are employed in DMSO as alkylidene transfer reagents." ... 

This organometallic coupling reaction is useful in organic synthesis because it forms carbon-carbon bonds, thereby making possible the preparation of larger molecules from smaller ones. As the following examples indicate, the coupling reaction can be carried out on aryl and vinylic halides as well as on alkyl halides. 

This process, named the Diels-Alder cycloaddition reaction after its discoverers, is extremely useful in organic synthesis because it forms two carbon-carbon bonds in a single step and is one of the few genera) methods available for making cyclic molecules. (As the name implies, a cycloaddition reaction is one in which two reactants add together to give a cyclic product.) The... 

Isomerization of vinylaziridines is widely used in organic synthesis. Six types of isomerization of vinylaziridines are shown in Scheme 2.40. Outlined in this section are i) azepine formation by aza-[3,3]-Claisen rearrangement of 1,2-divinyl- or 2,3-divinylaziridines 153 (Section 2.4.1), ii) pyrroline formation from 155 (Section 2.4.2), Hi) aza-[2,3]-Wittig rearrangement of anionic species 157 (Section 2.4.3),... 

There is an excellent, if non critical, compilation of absolute and relative rate data for reactions of oxygen-centered radicals covering the literature through 1982389 and for 1982-1992.39 1 Selected data from these and other sources are summarized in Table 3.7 and Table 3.8. The reactions of oxygen-centered radicals and their use in organic synthesis has been recently reviewed by Hartung el uIS )]... 

Although olefin metathesis had soon after its discovery attracted considerable interest in industrial chemistry, polymer chemistry and, due to the fact that transition metal carbene species are involved, organometallic chemistry, the reaction was hardly used in organic synthesis for many years. This situation changed when the first structurally defined and stable carbene complexes with high activity in olefin metathesis reactions were described in the late 1980s and early 1990s. A selection of precatalysts discovered in this period and representative applications are summarized in Table 1. 

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