Isocyanates amide synthesis

The Ferrario reaction generates phenoxathiins from diphenyl ethers (eq 19). The rearrangement of acyloxy aromatic systems is known as the Fries rearrangement (eq 20). Aryl aldehydes are produced by the Gatterman aldehyde synthesis (eq 21 The initial step of the Haworth phenanthrene synthesis makes use of a Friedel-Crafts acylation. The acylation of phenolic compounds is called the Houben-Hoesch reaction (eq 22). The Leuckart amide synthesis generates aryl amides from isocyanates (eq 23). ... 

A special problem arises in the preparation of secondary amines. These compounds are highly nucleophilic, and alkylation of an amine with alkyl halides cannot be expected to stop at any specifle stage. Secondary amides, however, can be monoalkylated and lydrolyzed or be reduced to secondary amines (p. 11 If.). In the elegant synthesis of phenyl- phrine an intermediate -hydroxy isocyanate (from a hydrazide and nitrous acid) cyclizes to pve an oxazolidinone which is monomethylated. Treatment with strong acid cleaves the cyclic irethan. 

LEUCKARDT PICTET HUBERT Ph nanlhndlne synthesis AmUation of aryls by isocyanates (Leuckardt) or by amides (Pictel-Hubert), catalyzed by Lews acids and leading to phenanitwldinas. 

The application of / -(diphenylphosphinyl)benzenesulphonic acid (58) to the synthesis of esters of amino-acids has made the work-up much simpler, since the resultant oxide is water-soluble. Diphenylphosphinyl isocyanate (59) can be prepared from diphenylphosphinic amide. 

In addition to its utility in the enantioselective formation of C-0 bonds (cf. Scheme 15), Trost s chiral ligand 102 has been used in the catalytic asymmetric synthesis of C-N bonds. An impressive application of this protocol is in the enantioselective total synthesis of pancrastatin by Trost (Scheme 17) H9i Thus, Pd-catalyzed desymmetrization of 112 leads to the formation of 113 efficiently and in > 95 % ee. The follow-up use of the N3 group to fabricate the requisite cyclic amide via isocyanate 117 demonstrates the impressive versatility of this asymmetric technology. 

The isorniinchnone cyclization/isocyanate cycloreversion process for substituted furan synthesis has been well studied, as exemplified by the conversion of 104 to 106 (Scheme 19.19). In a solid-phase adaptation of this transformation, two groups independently utilized this reaction to estabhsh a traceless self-cleaving method for the synthesis of substituted furans [176, 177]. Further investigation of the thermal requirements of this cycloreversion led to its application in the split-pool synthesis of a small library of amides [178]. 

Many of the common condensation polymers are listed in Table 1-1. In all instances the polymerization reactions shown are those proceeding by the step polymerization mechanism. This chapter will consider the characteristics of step polymerization in detail. The synthesis of condensation polymers by ring-opening polymerization will be subsequently treated in Chap. 7. A number of different chemical reactions may be used to synthesize polymeric materials by step polymerization. These include esterification, amidation, the formation of urethanes, aromatic substitution, and others. Polymerization usually proceeds by the reactions between two different functional groups, for example, hydroxyl and carboxyl groups, or isocyanate and hydroxyl groups. 

Support-bound C,F I-acidic compounds, such as acetoacetamides, react with isocyanates under basic conditions to yield amides through C-carbamoylation [71]. Similarly, polystyrene-bound aryllithium compounds can be converted into benzamides by treatment with isocyanates [111]. These reactions are closely related to C-thiocarbamoyla-tion, which has been used for the solid-phase synthesis of thioamides (see Section 13.9). Amides have also been prepared by C-alkylation of resin-bound N-acylaminals with allyltrimethylsilane or diethylzinc (Entry 11, Table 13.7). 

On the pages which follow, general methods are illustrated for the synthesis of a wide variety of classes of organic compounds including acyl isocyanates (from amides and oxalyl chloride p. 16), epoxides (from reductive coupling of aromatic aldehydes by hexamethylphosphorous triamide p. 31), a-fluoro acids (from 1-alkenes p. 37), 0-lactams (from olefins and chlorosulfonyl isocyanate p. 51), 1 y3,5-triketones (from dianions of 1,3-diketones and esters p. 57), sulfinate esters (from disulfides, alcohols, and lead tetraacetate p. 62), carboxylic acids (from carbonylation of alcohols or olefins via carbonium-ion intermediates p. 72), sulfoxides (from sulfides and sodium periodate p. 78), carbazoles... 

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