Handbook of Functionalized Organometallics Applications in S

14.3 Unsymmetrically Placed Substituents in Stoichiometric Electrophilic Multihapto-Complexes
OMe
N
Scheme 14.14
F
Cr(CO) 3
32
Cr(CO) 3
Me
Cl
Me
33
Cl
Me Me
Scheme 14.15
Cr(CO) 3
35
Cr(CO) 3
37
Cr(CO)3
39
Li
1) MeO
, iPr2NH (from
the generation of the enolate),
THF, -78 ºC, 30 min, then
2) I2, -30 ºC - rt, 10 h, 65%
Ref. 154
1) PhLi,
MeO OMe
toluene, -78 ºC, 4h
2) BrCH2CCSiMe3, HMPA, -78 - 20 ºC,
3) H2O, 93%
Ref. 159
1) LiCMeSO2Tol, THF
hexane/TMEDA, -78 °C, 1 h,
-10 °C, 10 min, 0 °C, 20 min
2) F3CCO2H
-78 °C -rt, 56%
Ref. 166
1) LiEt 3BD, THF, reflux, 2 h
2) F 3CCO 2H, 2 h, >99%
Ref. 169
Ref. 167
1) LiCMe2CN, THF
hexane, -78 °C, 30 min
2) F3CCO2H -78 °C - rt, 89%
TolO 2S
( +
-)
Me
O
( )
+
D
OMe
Ph
Me
Cr(CO)3
38
Me Me
Cr(CO) 3
CMe 2CN
CO 2Me
36
SiMe3
Cr(CO)3
Despite these complications with cine and tele pathways, it turns out that the
more obvious ipso-S NAr pathway, in which the nucleophile adds at the position
that carries the leaving group (i.e., ipso addition), is also quite common (see Section
14.5.7). In the case of 40 (Scheme 14.16), the indenyl substituent isomerized
587