Synthesis and properties of atropisomeric phosphinous acids

In this paper we describe two groups of atropisomeric phosphinous acids—bis-[(N,N-diisopropyl-1-naphthamide)-2-]phosphinous acids ( to ) and their 8-methoxy- substituted relations ( to ). The first group of acids interconvert at room temperature and the second group do not. The interconversion and properties are illustrated by two dimensional TLC and some NMR spectra. The peri substituent turns out to be important.