40
ORGANIC SYNTHESIS—1995
I.A.7.a.3-17 Soai, K. et al., JCS(Pl), 3125, 1257 & 873, CC, 317 &
TA, 5, 789; Hoshino, O. et al., TA, 5, 411; Mehler, T. and Martens, J., TA,
5, 207; Pedrosa, R. et al., TA, 5, 67; Kellogg, R.M. et al., TA, 5, 31; Cho,
B.T. and Kim, N., TL, 35, 4115; Wandrey, C. et al., 5, 911; Seebach, R.E.
et al., HCA, 77, 2071; Waldmann, H. et al., HCA, 77, 2111; van Koten, G.
et al., TL, 35, 6521; Kang, J. et al., SL, 842 & CC, 2009; Ishizaki, M. and
Hoshino, O., CL, 1337; Laloe, E. and Srebnik, M., TL, 35, 5587.
PhCHO
^ „
catalyst
+
+ Et 2 Zn
L_^
PhCOMe
Ph Me
catalyst =
Η/#Λ f,«\H
HO
NBu 2
PlK^Et
ÔH
82%, 85% ee
+ PhCOMe
70%
recovery
many other chiral catalysts employed for similar additions to
aldehydes
I.A.7.a.3-18 Knöchel, P. et al., TL, 35, 9007 & 5849, JOC, 59, 3760 &
4143, see also: TL, 35, 4539 & TA, 5, 1161.
(FG-R^^
>H
RCHO
Zn
cat.
R" ^
"R-FG
41-82%, 50-96% ee
cat. = Ti(0'Pr)4, PhMe, -60 to -20°C
NHTf
NHTf
I.A.7.a.3-19 Clayden, J. and Julia, M., CC, 1905 & 2261.
H
S 0 2 p h
Et 2 Zn, RCHO
Pd(PPh 3 ) 4 *
R
63-97%