Issue 5, 2016

Synthesis of P-stereogenic diarylphosphinic amides by directed lithiation: transformation into tertiary phosphine oxides via methanolysis, aryne chemistry and complexation behaviour toward zinc(ii)

Abstract

The highly diastereoselective synthesis of P-stereogenic phosphinic amides via directed ortho lithiation (DoLi) of (SC)-P,P-diphenylphosphinic amides with t-BuLi followed by electrophilic quench reactions is described. Functionalised derivatives containing a wide variety of ortho substituents (Cl, Br, I, OH, N3, SiMe3, SnMe3, P(O)Ph2, Me, allyl, tBuOCO) have been prepared in high yields with diastereomeric ratios up to 98 : 2. The X-ray diffraction structure of the ortho-stannylated and ortho-iodo compounds showed that the pro-S P-phenyl ring was stereoselectively ortho-deprotonated by the organolithium base. The usefulness of the method is supported by two key transformations, the synthesis of P-stereogenic methyl phosphinates through replacement of the chiral auxiliary by a methoxy group and the first example of the insertion of benzyne into the P–N bond of a P-stereogenic phosphinic amide. A DFT study of this reaction showed that the insertion proceeds through a [2 + 2] cycloaddition and a subsequent ring-opening with retention of the P-configuration. Explorative coordination chemistry of the new P-stereogenic ligands provided access to a chiral phosphinic amide-phosphine oxide Zn(II) complex, the crystal structure of which is reported.

Graphical abstract: Synthesis of P-stereogenic diarylphosphinic amides by directed lithiation: transformation into tertiary phosphine oxides via methanolysis, aryne chemistry and complexation behaviour toward zinc(ii)

Supplementary files

Article information

Article type
Paper
Submitted
25 juil. 2015
Accepted
27 août 2015
First published
27 août 2015

Dalton Trans., 2016,45, 2008-2022

Author version available

Synthesis of P-stereogenic diarylphosphinic amides by directed lithiation: transformation into tertiary phosphine oxides via methanolysis, aryne chemistry and complexation behaviour toward zinc(II)

M. A. del Águila-Sánchez, Y. Navarro, J. García López, G. P. Guedes and F. López Ortiz, Dalton Trans., 2016, 45, 2008 DOI: 10.1039/C5DT02860D

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