RECENT PROGRESS ON THE CHEMICAL SYNTHESIS OF ANNONACEOUS ACETOGENINS AND THEIR STRUCTURALLY MODIFIED MIMICS - Medicinal Chemistry of Bioactive Natural Products - page 417

HO

OO

AD mi x -a AD mi x -β

C 12 H 25 CO 2 Et

O

( ) 2 CO 2 Et

O O

C 12 H 25

C 12 H 25

105 106

104

Sharpless AE

MOMO

MOMO

(+)-DET

O

O O

O OH

C 12 H 25

C 12 H 25

HO

107 108

OBPS

O O

C 12 H 25

110 O

PPh 3 I

O O

OMOM OMOM

109

OH

13

O 34 22

O

O

4

1

OH

HO O

erythro-trans-threo-trans-threo squamotacin

BPSO

CO 2 Et

O

C 10 H 21

O O

C 10 H 21

111 112

O

O

C 10 H 21

O 114

PhS

O O

MOMO OMOM

113

37

OH

34

O 24 15

O

O

1

10

OH O

HO

trilobin

threo-cis-erythro-trans-threo

Scheme 10-21. Total synthesis of squamotacin and trilobin by Keinan et al.

116 and selective deprotection of MOM ethers gave 119 and 120, respectively. In
the presence of Re 2 O 7 and trifluroacetic acid anhydride, 119 and 120 were con-
verted in only one step to bis-THF products, 121 and 122, respectively. The final
selective reduction of double bonds followed by removal of O-silyl ethers afforded
rollidecin C and rollidecin D.
In Wang et al.'s synthesis of asimilobin 60,61 (Scheme 10-23), the key diol 123
was also prepared by Sharpless AD in high enantioselectivity. Oxidation of 123
furnished the trans-threo-trans bis-THF intermediate 124 in catalysis of
Co(modp) 2 . The C 2 symmetrical diol 124 was desymmetralized and converted