Abstract
A series of thiophene- and benzothiophene-oxazoline containing ligands, were applied in the intermolecular asymmetric phenylation and cyclohexenylation of 2,3-dihydrofuran 1 . Phenylation proceeded in moderate to high chemical yields, with good regioselectivities and in up to 95% ee. Cyclohexenylations gave similarly high chemical yields and regioselectivities with the optimal result being a 96% yield of the major product in 97% ee. 2,2-Dialkyl-2,3-dihydrofurans were also tested as substrates and the phenylation and cyclohexenylation of 2,2-dimethyl-2,3-dihydrofuran proceeded in high yields and ee’s up to 91% and 89%, respectively. The phenylation and cyclohexenylation of the 2,2-diethyl analogue proceeded in excellent yields and ee’s up to 99% and 87%, respectively. For each substrate, palladium complexes formed from the t -butyl-substituted ligand 10 gave the highest yields, regioselectivities, and enantioselectivities over the broad range of reaction conditions studied. 2,2-Diisopropyl-2,3-dihydrofuran was prepared but was found to be unreactive in the intermolecular Heck reaction thus providing insight into to the steric limits for 2,3-dihydrofuran substrates.
Key words
P,N ligands - oxazoline - asymmetric catalysis - intermolecular Heck reaction - palladium
References
1a de Meijere A.
Meyer FE.
Angew. Chem., Int. Ed. Engl.
1994,
33:
2379
1b Cabri W.
Candiani I.
Acc. Chem. Res.
1995,
28:
2
1c Link JT.
Overman LE.
Metal Catalyzed Cross Coupling Reactions
Stang PJ.
Diederich F.
Wiley-VCH;
Weinheim:
1998.
Chap. 6.
p.231
2a Bräse S.
de Meijere A.
Handbook of Organopalladium Chemistry for Organic Synthesis
Negishi E.
Wiley-VCH;
Weinheim:
2002.
p.1223-1254
2b Dyker G.
Handbook of Organopalladium Chemistry for Organic Synthesis
Negishi E.
Wiley-VCH;
Weinheim:
2002.
p.1255-1282
3a Larhed M.
Hallberg A.
Handbook of Organopalladium Chemistry For Organic Synthesis
Negishi E.
Wiley-VCH;
Weinheim:
2002.
p.1133-1222
3b Shibasaki M.
Boden CDJ.
Kojima A.
Tetrahedron
1997,
53:
7371
4a Beletskaya IP.
Cheprakow AV.
Chem. Rev.
2000,
100:
3009
4b Amatore C.
Broeker G.
Jutand A.
Khalil F.
J. Am. Chem. Soc.
1997,
119:
5176
4c Hii KK.
Claridge TDW.
Brown JM.
Angew. Chem., Int. Ed. Engl.
1997,
109:
1033
4d Hii KK.
Claridge TDW.
Brown JM.
Smith A.
Deeth RJ.
Helv. Chim. Acta
2001,
84:
3043
5a Guiry PJ.
Hennessy AJ.
Cahill JP.
Top. Catal.
1997,
4:
311
5b Shibasaki M.
Vogl EM.
J. Organomet. Chem.
1999,
576:
1
5c Gibson SE.
Middleton RJ.
Contemp. Org. Synth.
1996,
3:
447
5d Donde Y.
Overman LE.
Catalytic Asymmetric Synthesis
Oijima I.
Wiley-VCH;
New York:
2000.
Chap. 8g.
5e Shibasaki M.
Miyazaki F.
Handbook of Organopalladium Chemistry for Organic Synthesis
Negishi E.
Wiley-VCH;
Weinheim:
2002.
p.1283-1315
6a Dounay AB.
Overman LE.
Chem. Rev.
2003,
103:
2945
6b Guiry PJ.
Kiely D.
Curr. Org. Chem.
2004,
8:
781
7 Ozawa F.
Kubo A.
Hayashi T.
Tetrahedron Lett.
1992,
33:
1485
8 Loiseleur O.
Meier O.
Pfaltz A.
Angew. Chem., Int. Ed. Engl.
1996,
35:
200
9a Gilbertson SR.
Fu Z.
Org. Lett.
2001,
3:
161
9b Gilbertson SR.
Xie D.
Fu Z.
J. Org. Chem.
2001,
66:
7420
9c Gilbertson SR.
Fu Z.
Xie D.
Tetrahedron Lett.
2001,
42:
365
9d Hashimoto Y.
Horie Y.
Hayashi M.
Saigo K.
Tetrahedron: Asymmetry
2000,
11:
2205
9e Tu T.
Deng W.-P.
Hou X.-L.
Dai l.-X.
Dong X.-C.
Chem.-Eur. J.
2003,
9:
3073
10 Kilroy TG.
Hennessy AJ.
Malone YM.
Farrell A.
Guiry PJ.
J. Mol. Catal. A: Chem.
2003,
196:
65
11a Kiely D.
Guiry PJ.
Tetrahedron Lett.
2002,
43:
9545
11b Kiely D.
Guiry PJ.
Tetrahedron Lett.
2003,
44:
7377
11c Kiely D.
Guiry PJ.
J. Organomet. Chem.
2003,
687:
545
12 Kündig PE.
Meier P.
Helv. Chim. Acta
1999,
82:
1360
13 Malkov AV.
Bella M.
Stara IG.
Kocovsky P.
Tetrahedron Lett.
2001,
42:
3045
14 Tietze LF.
Lohmann JK.
Synlett
2002,
2083
15 Cozzi PG.
Menges F.
Kaiser S.
Synlett
2003,
833
16 Kilroy TG.
End N.
Cozzi PG.
Guiry PJ.
Synlett
2004,
106
17 Frost CG.
Williams JMJ.
Tetrahedron Lett.
1993,
34:
2015
18 End, N.; Stoessel, C.; Berens, U.; di Pietro, P.; Cozzi, P. G. submitted to Tetrahedron: Asymmetry ; Special Issue on phosphorous ligands.
19 Ozawa F.
Kubo A.
Matsumoto Y.
Hayashi T.
Organometallics
1993,
12:
4188
20a Hennessy AJ.
Malone YM.
Farrell A.
Guiry PJ.
Tetrahedron Lett.
1999,
40:
9163
20b Hennessy AJ.
Malone YM.
Farrell A.
Guiry PJ.
Tetrahedron Lett.
2000,
41:
2261
20c Hennessy AJ.
Connolly DJ.
Malone YM.
Farrell A.
Guiry PJ.
Tetrahedron Lett.
2000,
41:
7757
21 Papageorgiou VP.
Assimopoulou AN.
Couladouros EA.
Hepworth D.
Nicolaou KC.
Angew. Chem., Int. Ed.
1999,
38:
270
22 Tanoue Y.
Terada A.
Tanuguchi H.
Okuma T.
Kaai H.
Anan M.
Kakara Y.
Doi M.
Morishita S.-I.
Bull. Chem. Soc. Jpn.
1993,
66:
3712
23a Katritzky AR.
Jiang J.
J. Org. Chem.
1995,
60:
6
23b Katritzky AR.
Jiang J.
J. Org. Chem.
1997,
62:
4133
24 Hallberg A.
Ripa L.
J. Org. Chem.
1997,
62:
595
25 Deckker G.
Buijs A.
Elsevier CJ.
Vrieze CK.
van Leeuwen PWNM.
Smeets WJ.
Spek AL.
Wang YF.
Stam CH.
Organometallics
1992,
11:
1937
26 Paquette LA.
Lanter JC.
Wang H.-L.
J. Org. Chem.
1996,
61:
1119
