Synthesis and Structural Peculiarities of Homeomorphic Phosphorus Bridgehead Macrobicyclic Compounds and Novel Dioxaphospha[3.1.1.]p,m,p-cyclophanes

✍ Scribed by Ingmar Bauer; Roland Fröhlich; Albina Yu. Ziganshina; Alexander V. Prosvirkin; Margit Gruner; Ella Kh. Kazakova; Wolf D. Habicher

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 207 KB
• Volume: 8
• Category: Article
• ISSN: 0947-6539
• DOI: 10.1002/1521-3765(20021216)8:24<5622::aid-chem5622>3.0.co;2-p

✦ Synopsis

The double-capping reaction of p,m,p-trinuclear diphenol 4 with PCl3 affords the three homeomorphic isomers 5-7 of a phosphite macrobicyclic compound in low yields. X-ray structures of out, out-isomer 5 and in, in-isomer 6 show very flat macrobicyclic structures with P-P distances of 4.9 A and 4.5/5.3 A (two conformers), respectively. The main product of the reaction, however, appears to be diphosphite 8, which contains two dioxaphospha[3.1.1.]p,m,p-cyclophane subunits. The structural peculiarities of 8 were studied after subsequent oxidation to the corresponding phosphate 12. At room temperature the free rotation either of the para-phenylene rings and the meta-phenylene ring in the macrocyclic moieties are hindered as could be demonstrated by means of NOESY measurements. The latter occupies an angled position in respect to the macrocyclic plane. This leads to the existence of conformational isomers due to different relative positions of the meta-phenylene ring to the P-OR substituent (cis,trans). We could isolate the cis,cis-isomer of 12 and establish its structure by X-ray diffraction.