Page 1210 - Advanced Organic Chemistry Part B - Reactions & Synthesis

1186 Scheme 13.21. Juvabione Synthesis: E. J Bergner and G. Helmchen a

CHAPTER 13 OH
A B
Multistep Syntheses C(CH OH) 2
2
H H 1) (CH 3 O C) CHO CCH
1) LDA 2 2 2 3
NaH,1% Pd(OAc) , dppe
I O 2 HO
O 2) CH 3
H H 2) LiAlH 4 H 1) NaIO
CH 4
O CH 3 O 3 2) CH N
2 2
D C 3) CH ONa
3
E CO 2 CH 3 1) Dess-Martin CO 2 CH 3
+
H , H O CH 3 2) SCH 3
2
(+)-threo-juvabione H HO H
)
+ 3% epijuvabione Ph P CH(CH 3 2
CH SCH 3 CH 3 2 CH 3
3
O n-BuLi
a. E. J. Bergner and G. Helmchen, J. Org. Chem., 65, 5072 (2000).
was introduced by a base-catalyzed opening of the epoxide to an allylic alcohol
(Step C-4), which then underwent oxidation with allylic transposition (Step D-1).
Several other syntheses of juvabione have also been completed. 23
13.2.2. Longifolene
Longifolene is a tricyclic sesquiterpene. It is a typical terpene hydrocarbon in
terms of the structural complexity. The synthetic challenge lies in construction of the
bicyclic ring system. Schemes 13.24 through 13.33 describe nine separate syntheses of
longifolene. We wish to particularly emphasize the methods for carbon-carbon bond
formation used in these syntheses. There are four stereogenic centers in longifolene,

Scheme 13.22. Juvabione Synthesis. C. Fuganti and S. Serra a

A B
CH baker's CH
CH 3 1) n-BuLi 3 yeast 3
TMEDA
CH 2 2) DMF O CH HO
H CH H 80:20 mixture H 1) PCC
CH 3 3 purified as 3,5- CH 3 2) (CH 3 2 2
) CHCH MgBr
dinitrobenzoate C 3) MCPBA
ester 4) LDA
CH
D 2
CO CH 3 1) PCC, TosOH
2
2) Ag O CH 3 OH
CH 3 2 H
3) CH N CH 3 OH CH 3
CH 3 O CH H 2 2
3
a. C. Fuganti and S. Serra, J. Chem. Soc., Perkin Trans. 1, 97 (2000).

23
A. A. Drabkina and Y. S. Tsizin, J. Gen. Chem. USSR (English Transl.), 43, 422, 691 (1973);
R. J. Crawford, U. S. Patent, 3,676,506; Chem. Abstr., 77, 113889e (1972); A. J. Birch, P. L. Macdonald,
and V. H. Powell, J. Chem. Soc. C, 1469 (1970); B. M. Trost and Y. Tamaru, Tetrahedron Lett., 3797
(1975); M. Fujii, T. Aida, M. Yoshihara, and A. Ohno, Bull. Chem. Soc. Jpn., 63, 1255 (1990).