Single diastereomers of unsymmetrical tris-spirocyclic cyclotriphosphazenes based on 1,1′-bi-2-naphthol-Synthesis and structures

Diastereoselective synthesis and characterization of chiral unsymmetrical tris‐spirocyclic cyclotriphosphazenes based on chiral 1,1′‐bi‐2‐naphthol (BINOL) are reported. Specifically, the chiral compounds (−)N3P3[1,1′‐O2(C10H6)2](O‐2,2′C6H4‐C6H4O)Cl2 [(−)‐4] and (−)N3P3[1,1′‐O2(C10H6)2](OCH2CH2NMe)2 [(−)‐5] are prepared by starting with the chiral mono‐spiro compound (−)N3P3[1,1′‐O2(C10H6)2]Cl4 [(−)‐3]. Synthesis of four other chiral spirocyclics, N3P3[1,1′‐O2(C10H6)2](OCH2CH2 NMe)(O‐2,2′C6H4‐C6H4O)[(−)‐6 and (+)‐6], N3P3[1,1′‐O2(C10H6)2](NMe2)4 [(−)‐7], N3P3[1,1′‐O2(C10H6)2](O‐2,2′C6H4‐C6H4O)(NMeCH2CH2OH)2 [(−)‐8 and (+)‐8], and N3P3[1,1′‐O2(C10H6)2](O‐2,2′C6H4‐C6H4O)[NHCH2CH2CH2Si(OEt)3]2 (9) is also reported herein. Compounds 4–6 are obtained in the solid state diastereoselectively and their X‐ray structures have been determined and discussed. The diastereoselectivity is also shown by structural characterization of two distinct isomers in the case of 6 [(−)‐6 and (+)‐6, respectively] by starting with precursor of 3 having (R) or (S)‐BINOL residue. The 1H NMR spectra of 7 and 8 exhibit doublets with virtual coupling for the methyl protons, consistent with the chiral nature of the binaphthoxy residue. The potential of 9, which hydrolyzes readily in CDCl3 solution, as a useful precursor for chiral polymer applications is highlighted. Chirality, 2008. © 2008 Wiley‐Liss, Inc.