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O
O
OTBS
OTBS
OTBS
O
O
172
173
Br
171
O
C
8
H
17
HO
HO
TBSO
I
C
10
H
21
O
C
10
H
21
O
OH
OTBS
174
175
OTBS
mucocin
TBDMS
O
O
OHC
O
53
O
Scheme 10-29. Total synthesis of mucocin by Koert et al.
Koert et al.'s strategy
78,79
for mucocin disconnected the target into two major
parts: One contains a THP moiety (diol 174 or its equivalent 175), and the other
contains a THF ring (aldehyde 53). The coupling of those two segments was
achieved by Grignard reaction (175 and 53). In this synthesis, the formation of
the THP ring also used the cis-olefin site-direction effect on substrate 173, which
gives the 6-endo epoxide opening product 174 predominately (Scheme 10-29).
A chiron approach to mucocin was developed by Takahashi and colleagues
80,81
(Scheme 10-30). The simple addition of aldehyde 176 (prepared from D-lactose
TBDMS
MOMO
TBDMSO
O
TBDMSO
OTBDMS
MOMO
+
C
10
H
21
O
C
10
H
21
O
O
O
O
OMOM
OTr
HO
OMOM
OTr
176
177
178
MOMO
C
10
H
21
O
O
OMOM
mucocin
MOMO
179
O
PhSe
O
MOMO
O
I
180
Me
( )
3
OMOM
O
( )
3
TBDPSO
OMOM
181
Scheme 10-30. Total synthesis of mucocin by Takahashi et al. (route one).
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