Page 157 - Advanced Organic Chemistry Part B - Reactions & Synthesis

129

SECTION 2.1
Aldol Addition and
Condensation Reactions

Cu

Hindered
Diastereoface

Fig. 2.3. Origin of facial selectivity of bis-
oxazoline catalyst. Reproduced from Tetrahedron:
Asymmetry, 9, 357 (1998), by permission of
Elsevier. (See also color insert.)

Halogenated BINOL derivatives of Zr O-t-Bu such as 19 also give good yields
4
and enantioselectivity. 159
I
O-t-Bu OH
O CH OTMS 19
2
Zr PhCH O + 3 CO CH 3
O O-t-Bu CH 3 OCH 3 PrOH Ph CH 3 CH 3
19
I 89% 97% e.e.

O 6
O 8 O 8
O 7
Ti 2
O 7
Ti 2
O 6 O 5
O 1
O 1
O 5
O 4
Ti 1
Ti 1
O 3
O 2
O 3 O 2
O 9
O 4
O 11
Ti 3
O 10 O 12
Fig. 2.4. Left: dinuclear complex of composition (BINOLate)Ti 2 O-i-Pr 6 . Right: trinuclear complex of
composition (BINOLate)Ti 3 O-i-Pr 10 . Reproduced from Org. Lett., 3, 699 (2001), by permission of the
American Chemical Society.
159
S. Kobayashi, H. Ishitani, Y. Yamashita, M. Ueno, and H. Shimizu, Tetrahedron, 57, 861 (2001).