112
H. Zhu et al.
R = o-Me-Bz
N
O
R
N
O
R
O
H
N
O
R
O
PhSe
N
O
R
O
O
H
N
O
O
O
HO
358 (aspochalasin P)
H
N
O
O
O
HO
344 (aspochalasin B)
H
N
O
O
O
BzO
N
O
O
HO
HO
N
O
O
H
N
O
O
I1, t-BuLi,
then E2, 60%;
LiHMDS, PhSeCl,
78 %
H 2 O 2
E7, LiHMDS,
72% ((E)/(Z) > 10/1)
(CuOTf) 2 •PhMe,
63 % over 2 steps
Grubb's catalyst
(II), 85 %
1) Grubb's catalyst
(II), 85 %
2) OsO 4 , NMO, 45 %;
1) NaOH, 90%;
2) BzCl, Et 3 N, DMAP, 85%;
3) DMP, 83%
NaSMe,
75%
1) LiHMDS, PhSeCl;
2) H 2 O 2 ,
40 % over two steps
Br
Cl
O
N
S
S
O
O
I1
I2
I7
I3
I4
I6
I8
I9
I10
I5
17
18
Boc
Boc
I11
I12
G4
+
Scheme 14 Total syntheses of aspochalasin B
HN
O
O
OH
O
344 (aspochalasin B )
O
OH
HO
O
HN
O
O
OAc
O
O
HO
OH
O
HO
O
OH
HO
O
HN
O
O
OH
O
451 (asperchalasine E)
HO
O
HO
O
HN
O
O
OH
O
449 (asperchalasine C)
HO
O
OH
O
HN
O
O
OH
O
450 (asperchalasine D)
CSA, BHT, toluene, 60°C
80%
(373:407:374:375 = 10:2:1:1)
I14
448 (asperchalasine B)
+
Scheme 15 One-pot syntheses of asperchalasines B–E