2-Bis(dimethylamino)phosphinoyl-1-lithio-1,2,3,4-tetrahydro-isoquinoline. A Highly Nucleophilic d1-Reagent for the Preparation of 1-Substituted Tetrahydroisoquinolines

Article abstract of DOI:10.1002/hlca.19810640305

The title compound 4 is generated from the phosphoric amide 5 in tetrahydrofuran with butyllithium.The lithium reagent 4 is stable at room temperature; its reactions with electrophiles furnish the products 6-22, 26,27, see Table 1 and the Scheme.A second alkylation is also possible, see 23-25.The cleavage to tetrahydroisoquinolines is accomplished in refluxing aqueous-methanolic hydrochloric acid, see Table 2.Phosphinoylation, lithiation, reaction with electrophiles and cleavage constitute an efficient sequence for 1-alkylation of the isoquinoline nucleus.