Readily available starting materials aromatic

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. 

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. 

This procedure affords a one-step synthesis of aromatic sul-finic esters from readily available starting materials. It is successful with a variety of types of aromatic sulfinic esters.6 The method is rather unattractive for aliphatic disulfides, however, because the nature of by-products formed makes rigorous purification of the sulfinic esters impracticable.8... 

Next consider the synthesis of M from readily available starting materials. The relevant facts about M are that (a) it contains an aromatic ring, an acetate ester, and a vinyl group (b) it has a straight chain attached to the ring and (c) all the functional groups are isolated. 

Even though the aramatization mechanism from the putative cyclohexadienyl radical intermediate is not well understood (oxidation by the adventitious air is one possibility), the radical addition to an aromatic ring strategy does possess some advantages (a) no transition metal catalysis is required, (b) better yields are obtained than with similar procedures although the reaction is not regiospecific, (c) readily available starting materials may be used. 

The synthesis of cyclophane 17 (9,10,ll,12,26,27,28,29-octahydro-3H,8H,16H,20H,25H, 33H-4,7 21,24- dimetheno -13,19,15 30,2,32-di[ 1 ]propane[ 1 ]yl[3Jylidine- 1H, 18H-dipyrimidino [l,2-a l ,6 -o] [l,8,15,22]tetraazacyclo-octacosine) is described. Both isomers of cyclophane 17 were synthesized over nine steps in 46 % overall yield from readily available starting materials. We designed and synthesized a side group for attachment to cyclophane 17, which we wish to use for the directed-complexation of the cyclophane with a specified aromatic guest. We had hoped to use the Buchwald-Hartwig reaction to attach this side arm to the secondary amines of 17, but despite our many efforts we were unable to achieve this goal in a reproducible manner. 

Shortly thereafter, an inexpensive procedure for the industrial production of 1 from readily available starting materials was elaborated (Bayer, 1878)." In related efforts, chemists identified another compound, alizarine 3, which was isolated from a certain species of plants Rubia tinctoria). It was used for centuries as a natural dye. Originally very expensive, it soon became an inexpensive product owing to the ease of its synthesis from the aromatic hydrocarbon anthracene, present in coal tar (Grebe and Lieberman, 1868). ... 

Reduction of aromatic nitro compounds is by far the most useful method of preparing amines, since it uses readily available starting materials, and yields the most important kind of amines, primary aromatic amines. These amines can be converted into aromatic diazonium salts, which are among the most versatile class of organic compounds known (see Secs. 23.11-23.17). The sequence... 

Beller reported a selective ruthenium-catalyzed synthesis of highly substituted pyrroles (e.g., 52). The sequence utihzes readily available starting materials benzylic ketone 49, amine 50 (ahphatic, aromatic, or ammonia), and vicinal diol 51.Tri-, tetra-, and pentasubstituted pyrroles can be easily prepared in moderate to high yields. A variety of aromatics, alkyl groups, and halogens are tolerated (13AG(I)597). 

Silanes with electronegative ligands did not react, except in the presence of the tertiary base EtjN [e.g., Eq. (19)] (62, 63). This then provides an attractive route to Si—Pt(II) compounds since the starting materials are readily available and the reaction gives pure products in high (60-90%) yields. Only aromatic phosphine Pt complexes reacted readily, and the use of an excess of silane failed to bring about replacement of the second halogen atom. 

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