26
ORGANIC SYNTHESIS—1995
I.A.7.a.la-10 Shibasaki, M. et al., JOC, 59, 2661; see also: Mori, N. et
al., SC, 24, 3315.
RCHO +
C
Cl
)H
Sm(HMDS) 3
C s H n
THF,-30to-50°C
R
' X
C s H l 1
Cl Cl
50-100%
I.A.7.a.la-ll Kobayashi, S. et al., BCJ, 67, 2342 & JOC, 59, 3590;
Floriani, C. et al., SL, 857.
\
2
/
O T M S
Yb(OTf)3
φ
\ 4
H 2 0,EtOH,
K
PhMe, rt
R
4
Yb(OTf>3 is water tolerant & can be used repeatedly
similarly with the novel, homogeneous catalyst: Zr(tmtaa)(OTf)2
I.A.7.a.la-12 Evans, D.A. et al., TL, 35, 8537 and 8541.
)TMS
o
OPMB
+
BF 3 »OEt 2
PMB