A Novel Access to Tertiary and Secondary or^o-Aminophenylphosphines by Protected Group Synthesis and Palladium Catalyzed P-C Coupling Reactions

tert-Butoxycarbonylaniline, orf/zo-Lithiation, Chlorophosphines The dilithium salt la formed by ortho-metallation of N-terf-butoxycarbonylaniline (BOCaniline) 1 with two equivalents of ter/-butyllithium reacts with the chlorophosphines Ph3_„PCl„ (n = 1 3) to yield the BOC protected ort/zo-aminophenylphosphines 2 4 in high yields. On deprotection of 2 4 with trimethylchlorosilane in the presence of phenol the HC1 adducts of the o/t/zo-aminophenylphosphines 5 7 are formed which may be deprotonated with KOH or NaOH to give the neutral phosphines 5a 7a. The novel secondary phosphine 8 with two orf/zo-aminophenyl groups is accessible by cleavage of the P-C bond in 7a with metallic lithium and subsequent hydrolysis. The bifunctional P,N ligands 6 or 6a are alternatively accessible by Pd-catalyzed P-C coupling of ortho-iodoaniline with phenylphosphine. If a 1:1 stoichiometry is employed in the coupling reaction of orr/zo-iodoaniline and phenylphosphine the chiral secondary phosphine 9 is formed.