Communications
by syringe and then the PBF was washed with additional toluene
cantly belowthose obtained with DTBM–SEGPHOS. DTBM–
MeO–BIPHEP (BIPHEP = 6,6’-dimethoybiphenyl-2,2’-diyl(di-
phenylphosphane)) afforded a comparable ee value, however,
the extent of conversion was low in reactions run at À258C.
[20] Made following a standard literature method[10c] by using chloro
bis(3,5-dimethylphenyl)phosphane; T. V. RajanBabu, T. A.
Ayers, G. A. Halliday, K. K. You, J. C. Calabrese, J. Org.
Chem. 1997, 62, 6012.
(1 mL). The reaction mixture was stirred at room temperature for
17 h. MeOH (1 mL) was slowly added and after 30 min 1n NaOH in
MeOH (0.5 mL) was added. The mixture was stirred for a few hours,
filtered through a plug of silica and concentrated under vacuum.
Purification by silica gel chromatography (10% acetone in CH2Cl2)
gave the corresponding phosphinyl amine (235 mg, 99% yield).
HPLC analysis indicated 96.2% ee. (Daicel Chiralcel OD, hexane/
isopropylalcohol 90/10, 1.0 mLminÀ1
,
220 nm; Rt = 5.3 min, (R),
[21] The increased concentration was achieved by decreasing the
amount of toluene used. 1,1,3,3-tetramethyl disilazane (TMDS;
6 equiv) gave best results.
7.3 min (S)).
Supporting Information available: Procedures and spectral data
for all hydrosilylations.
[22] See Supporting Information for details.
[23] As reported for BINAP, the (S)-enantiomer of DTBM–SEG-
PHOS is available by resolution following the protocol for the
(R)-enantiomer, but with reliance on the opposite enantiomer of
dibenzoyl tartrate; see H. Takaya, K. Mashima, K. Koyano, M.
Yagi, H. Kumobayashi, T. Taketomi, S. Akutagawa, R. Noyori, J.
Org. Chem. 1986, 51, 629.
Received: November 10, 2003 [Z53294]
Published Online: February 16, 2004
Keywords: copper · hydrides · hydrosilylation · P ligands ·
.
reduction
[1] “Asymmetric Hydrosilylation and Related Reactions”: H.
Nishiyama, K. Itoh in Catalytic Asymmetric Synthesis (Ed.: I.
Ojima), Wiley-VCH, NewYork, 2000, chap. 2.
[2] “Asymmetric Hydrogenation”: T. Ohkuma, M. Kitamura, R.
Noyori in Catalytic Asymmetric Synthesis (Ed.: I. Ojima), Wiley-
VCH, NewYork, 2000, chap. 1.
[3] For a recent report, see D. A. Evans, F. E. Michael, J. S. Tedrow,
K. R. Campos, J. Am. Chem. Soc. 2003, 125, 3534.
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[6] M. C. Hansen, S. L. Buchwald, Org. Lett. 2000, 2, 713, and
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[7] I. Takei, Y. Nishibayashi, Y. Arikawa, S. Uemura, M. Hidai,
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[8] H. Nishikori, R. Yoshihara, A. Hosomi, Synlett 2003, 561.
[9] F. Iwasaki, O. Onomura, K. Mishima, T. Kanematsu, T. Maki, Y.
Matsumura, Tetrahedron Lett. 2001, 42, 2525.
[10] a) F. Spindler, H.-U. Blaser, Adv. Synth. Catal. 2001, 343, 68;
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[11] B. Kryzyzanowska, W. J. Stec, Synthesis 1978, 521.
[12] D. H. Appella, Y. Moritani, R. Shintani, E. M. Ferreira, S. L.
Buchwald, J. Am. Chem. Soc. 1999, 121, 9473.
[13] T. Saito, T. Yokozawa, T. Ishizaki, T. Moroi, N. Sayo, T. Miura, H.
Kumobayashi, Adv. Synth. Catal. 2001, 343, 264; DTBM – SEG-
PHOS is (4,4’-bi-1,3-benzodioxol)-5,5’-diylbis(di(3,5-di-tert-4-
methoxyphenyl)phosphane).
[14] N. J. Lawrence, M. D. Drew, S. M. Bushell, J. Chem. Soc. Perkin
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[15] W. S. Mahoney, D. M. Brestensky, J. M. Stryker, J. Am. Chem.
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[18] See also: V. Jurkauskas, J. P. Sadighi, S. L. Buchwald, Org. Lett.
2003, 5, 2417; G. Hughes, M. Kimura, S. L. Buchwald, J. Am.
Chem. Soc. 2003, 125, 11253.
[19] Josiphos
(1-(2-(diphenylphosphanyl)ferrocenyl)ethyldicyclo-
hexylphosphane), Me–DuPHOS (DuPHOS = 1,2-bis(2,5-dime-
thylphospholano)benzene, and BINAP (2,2'-bis(diphenylphos-
phanyl)-1,1'-binaphthyl), all gave ee values that were signifi-
2230
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Angew. Chem. Int. Ed. 2004, 43, 2228 –2230