Abstract
Starting from the inexpensive 2,2-difluoro-1,3-benzodioxole or its 5-bromo derivative, two new atropisomeric bisphosphines have been prepared which, after racemate resolution, exhibit attractive features as ligands for enantioselective catalysts. The key step in their synthesis is a low temperature Ullmann reaction. An improved protocol secures coupling yields of 70-80%.
Key words
atropisomers - 2,2-difluoro-1,3-benzodioxole - bromo/lithium permutation - metalation - biarylbisphosphines
References
1
Castagnetti E.
Schlosser M.
Chem.-Eur. J.
2002,
8:
799
2
Castagnetti E.
Schlosser M.
Eur. J. Org. Chem.
2001,
691
3
Schlosser M.
Gorecka J.
Castagnetti E.
Eur. J. Org. Chem.
2003,
452
4
Gorecka J.
Leroux F.
Schlosser M.
Eur. J. Org. Chem.
2004,
in press
5 Leroux, F., manuscript in preparation.
6
Krizewsky J.
Turner EE.
J. Chem. Soc.
1919,
115:
559
7
Gilman H.
Straley JM.
Recl. Trav. Chim. Pays-Bas
1936,
55:
821
8
Wittig G.
Lehmann G.
Chem. Ber.
1957,
90:
875
9
Wittig G.
Klar G.
Liebigs Ann. Chem.
1967,
704:
91
10
Wittig G.
Rümpler K.-D.
Liebigs Ann. Chem.
1971,
751:
1
11
Fanta PE.
Synthesis
1974,
9
12
Ley SV.
Thomas AW.
Angew. Chem. Int. Ed.
2003,
42:
5400 ; Angew. Chem. 2003, 115, 5642
13 Saito T, Yokozawa T, Zhang S.-y, and Sayo N. inventors; Takasago Int. Corp. Eur. Pat. Appl., 850945.
; Chem. Abstr. 1998, 129, 124055y
14 Sayo N, Saito T, and Yokozawa T. inventors; Takasago Int. Corp. Eur. Pat. Appl., 945457.
; Chem. Abstr. 1999, 131, 251749u
15
Noyori R.
Asymmetric Catalysis in Organic Synthesis
Wiley;
New York:
1994.
16
Comprehensive Asymmetric Catalysis
Jacobsen EN.
Pfaltz A.
Yamamoto H.
Springer;
Berlin:
1999.
17
Catalytic Asymmetric Synthesis
2nd ed:
Ojima I.
Wiley VCH;
New York:
2000.
18 Michel, D.; Lonza AG, Visp, unpublished results, 2002.
19
Takaya H.
Akutagawa S.
Noyori R.
Org. Synth., Coll. Vol. VIII
Wiley;
New York:
1993.
p.57-63
20 Mettler, H. P.; Haesakkers, P.; Lonza AG, Visp, unpublished results, 2002/2003.
21
Desponds O.
Franzini L.
Schlosser M.
Synthesis
1997,
150
22
Heiss C.
Schlosser M.
Eur. J. Org. Chem.
2003,
447
23
Schlosser M.
Marull M.
Eur. J. Org. Chem.
2003,
1569
