Page 448 - Advanced Organic Chemistry Part B - Reactions & Synthesis

Scheme 5.6. (Continued) 421
9 i 2 equiv MOM – MOM SECTION 5.3
MOM O – O OH
MOM –
O – O O CBS-Me Group III
oxazaborolidine Hydride-Donor Reagents
TBDPSO
TBDPSO CH 3 CH 3
5 eq BH 3 -S(CH 3 ) 2 CH 3
CH 3
CH 3 CH 3
80%, > 99% ds
10 j O 2 equiv OH
S-CBS-Me-
OTBDMS oxazaborolidine OTBDMS
CH 3 CH 3
CH 3 CH 3 99% dr 10:1
5 eq BH 3 -S(CH 3 ) 2

11 k 0.5 equiv S
S R-CBS-Me CH 3
CH 3 CH 3 OTBDMS
CH 3 OTBDMS oxazaborolidine N
N
1.5 eq BH 3 -S(CH 3 ) 2 OH
O 98% 95% e.e.

12 l OTBDPS OTBDPS
30 mol %
R-CBS-Bu
oxazaborolidine CH 3
CH 3
catechol- C 2 H 5
C 2 H 5
borane
OSiEt 3 OH 88% > 99% de
OSiEt 3 O
13 m TBDPSO H CH 3
OMPM TBDPSO H CH 3
OMPM
S-CBS-Bu
O oxazaborolidine
TBDPSO H CH 2 catechol- TBDPSO H O
O borane CH 2
CH 3 O 2 C HO
CH 3 CH 3 O 2 C
CH 3
O
O (CH 2 ) 3 O 2 CC(CH 3 ) 3
(CH 2 ) 3 O 2 CC(CH 3 ) 3
H 2 C
H 2 C 17:1 dr
14 n
CH 3 CH 3
CH 3
CH 2 CH 3
CH 2
S-CBS-Me
oxazaborolidine
CH 3 1.5 eq BH 3 -S(CH 3 ) 2
CH 3
CH 3
CH 3
O 91%
HO
O O
(Continued)