Heterocyclic monoesters

A most intriguing cycloaddition reaction of phosphoryl isocyanates with poly-a-haloaldehydes provides a heterocyclic phosphonate monoester/monoamide as an isolable but reactive species (Equation 3.20).353... 

Neidlein, R., Keller, H., and Boese, R., Mild preparation of [l-[(benzyloxy)imino]alkyl]phosphonic dichlorides. Application to the synthesis of cyclic phosphonic diesters and cyclic monoester amides. Heterocycles. 35, 1185, 1993. 

A recent paper describes further conversion of (60). The corresponding keto-tricarboxylic acid was converted to the monoester and this was bisdecarboxylated to the diene (62). Catalytic reduction and formation of the heterocyclic ring by the well-known acyl azide photolysis gave ketolactam (63). This was transformed into the enantiomer of the known degradation product (64). 

Amphoteric fluorinated surfactants with heterocyclic nitrogen have also been prepared by the Michael addition of 2-perfluoroalkylethanethiol to either a maleic monoamide or monoester [163,202-204] ... 

Thus stereoisomers of compound 14, the free acid (and monoester) of compound 6 would also have the value 26594. Note that the LN is a reliable retrieval tool for positional isomers, such as compounds 7 and 8 (also 1 and 2 in the heterocyclic BRF). Furthermore, it is legitimate to state that there are no further positional isomers of these particular species in the data base, otherwise they would have been hits in this list. Similarly, the data base contains no further examples of X-phenyl-indole-Y,Z-dicarboxylic acid (compound 15). 

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