Novel copper complexes of chiral diphosphines: preparation, structure, and use to form rhodium complex catalysts for chiral hydrogenations

Abstract

Supplementary Material Available: Bond lengths (Table IV); valence angles (Table V); dihedral angles (Table VI) of 13, 14, and 8, including corresponding values calculated by the MM2 method for 6, 7, and 8; standard deviations of the calculated structural parameters of 6, 7, and 8 from the observed values (Table VII); listings of final atomic coordinates of 13,14, and 8 (Table VIII); thermal parameters (Tables IX and X) (l7 pages).Ordering information is given on any current masterhead page.

Asymmetric Synthesis of Bi(thio)xanthylidene Overcrowded Alkenes

“…(S,S)-Threitol ditosylate (S,S)-1 [13] was the first chiral template that was employed ( Figure 3). Two 7-methoxy-9-oxo-9H-thioxanthene-2-carboxylic acid (2) moieties were utilized as upper and lower part.…”

“…[17] Recrystallization of the 80:20 mixture of (S,S,P)-4 (major)/(S,S,M)-4 (minor) from acetone gave crystals of pure (S,S,M)-4 (minor product) that were suitable for X-ray analysis. [18] On the basis of the molecular structure and the known configuration of (S,S)-1 [13] the absolute configuration of (S,S,M)-4 could be assigned (Figure 4). Moreover, the analysis of structure (S,S,M)-4 revealed a "linear" coupling of the template with the alkene part, whereas the major product exhibits a "crossed" coupled structure ( Figure 3 To increase the yield of the intramolecular coupling reaction and to examine the role of the chiral template we embarked on the use of (R)-binaphthol [(R)-5] and (S)-binaphthol [(S)-5] as chiral templates.…”

“…Only formation of (Z) isomers was observed akin to stereocontrol by the threitol template (Figure 3). Diastereoisomers (R,P)-7 (major) and (R,M)-7 (minor) were identified by 1 H, 13 C NMR spectroscopy and HRMS (see Experimental Section and Supporting Information). By means of COSY and NOESY NMR all twelve different proton signals of both stereoisomers could be assigned unequivocally.…”

“…In contrast to its thio analogues, extensive formation of oligomers took place through intermolecular coupling reactions. The structure of (R)-10 was established by 1 H, 13 C, COSY, and NOESY NMR spectroscopy as well as HRMS determination. Up-field shifts of all aromatic protons were observed as compared to its precursor (R)-9 and again most prominent up-field shifts of 0.82 and 1.05 ppm were displayed by protons H a and H b , respectively (Table 2).…”

“…13 -2 mmol] was added, and the reaction mixture was stirred for 3 h at 5°C. The diethyl ether was removed under reduced pressure at room temperature and the residue was dissolved in CH 2 Cl 2 (10 mL) and 2  HCl (aq) (10 mL).…”