3GGS
COXIMUNIC.'ITIONS TO THE EDITOR
11.07; (2'1 addition of bromine to A2-friedelene,5 m.p. 257-25So, followed by dehpdrobromination to give the exomethylenic diene 111, m.p. 240-244", [ C Y ] ? ~ D+48.4', Amax 2-31 m p (log E 4.30), infrared max. SS3 cm.-l. Found: C, Si.84; H, 12.32.
I
I1
I \'
I11
1701.
77
oxide produces a p, y-unsaturated acid,8 C26H4202, 1711. Sodium dichromate oxidation of the methyl ester of VI1 yields the unsaturated keto ester VIII, m.p. 130-151", [ a I z 5-42.7", ~ ultraviolet max. 247 mp (log E 3.97), infrared max. 1742; Found: C, 78.49; H, 10.05. Alcoholysis of VI11 provides an unsaturated ketone (IX), m.p. 191-192", [a] 25D - 19.5", ultraviolet max. 248 mp (log E 3.94), infrared max. 1664cm.-I; Found: C, 84.33; H, 11.38, which upon hydrogenation yields the corresponding saturated ketone X, m.p. 103-197", [ a ] " D +42.5', infrared max. 1707 cm.-l; Found: C, 84.02; H, 11.88.
Bromination of friedelin produces a 2-bromofriedelin, m.p. 210" (dec.), [a]"D -140°, infrared, ultraviolet max. 1710 cm.-', 311 i r i w (axial B r ! ; found: C , 71.07; H, 9.tj5; Dr, 15.38; location ol bromine a t Ca proved by conversion to A2-friedeletic.5 Broinination of friedelin enol benzoate furnishes ~-bromnfrieclelin, m.p. 1D(i--19io (dcc.I , s XI1 SI11 [ L Y ] ~ ~+90.5", D infrared, ultraviolet inas. 1715 cm.-', 310 m,u (axial B r ) ; Found: C , 70.44; H, 'The presence of a hydrogen a t the original C8 0.38; Br, l3.iO. Although 2-broniofriedelin is un- is indicated by deuterium exchange of X with deureactive toward silver acetate, 4-bromofriedelin is terium bromide (2.9 deuterium atoms,'molecule) readily dehydrobrominated to an unsaturated, un- and by the three-step conversion of X via the keto conjugated ketone IV, which is not isomerized to a acid XI to the keto methyl ester XII, m.p. 132conjugated structure, m.p. %-%so, [ a ] ? ' ~ 133", [a]'% +21.1", infrared max. 1736, 1713, -48.6", infrared, ultraviolet max. 1710 cm.-', 290 1696 (weak) em.-'; Found: C, 77.38, H, 10.91. mp; Found: C, S4.Si; H , 11.20. llT:olff-Kishner I t is apparent t h a t rings B and C and rings C reduction of IV produces a new olefin, m.p. 221and D in friedelin are trans-locked, both from chem222O, different from A?-and A3-friedelenes.5 The ical el-idence" arid from the molecular dimensions production of IT from 4-bromofriedelin indicates ( I .+ ur,it celU0of friedelan-3a-ol chloroacetate, 16.3 that migration of a methyl group a t Cj has occurred X ii.,jX 6.0 A. as determined by X-ray s t u ~ l i e s . ~ ~ ~ during dehydrobromination. The four remaining methyl groups of friedelin 2-Bromofriedelin is not epimerized by hydrogen may be located as follows. Methyl groups must be bromide, which proves the trans-locking of rings present a t CI3and a t CI4since 1,2,7-trimethylnaphA and B and the presence of a hydrogen a t C147.fithal ene and 1,2,S-trimethylphenanthrene are The change in molecular rotation d u e to a.rial bro- formed by selenium dehydrogenation of friedelanmine a t C?(A;lln -6.51°) is opposite in direction to :3a-o1.? The presence of a third methyl group a t that due to :%.cia1broniine at C ' j ( A . l / ~ , - + ( ; 1 3 " ) . C,::iii{l thc fourth a t C l uor Cznis highly probable 'I'hesc data toget1ic.r with data 011 axial 0 -h1~i)lnokc o n hiosyn tlictic grounds'" because of the probable )ids' rt':-ml tiiat ( I 1 brcttni~ir,is CY r)rictitiyl i i i (~0111i~1')n gcnrsis of friedelin and thc other pcntacyImth 2- arid 4-broinofrietleliiis aild ( 2 ) tht. i!ietlIyl clic tritcrpenes froin squalene. Thus, expanded a t Cs is B and the hydrogen a t Clois a. structure XI11 follows for friedelin. Stepwise oxidation o l norfriedelendioiie (1. ):i by : X i ( > IV. Perold, K . Sleycrhans, 0.Jeger and I. Ruzicka, ffel?'. hyclrogen peroxide and ozone produces a tetracyclic (^i methyl iodoscp.t?lole~nolate 10.1 X 6.3 X 7.7 a. [.I.11 saturated ketone, C2jH4?O9(1'1 i, which possesses isle. Chem. wid i d , 279 ( l Y j 4 ) I. the oxo function a t Clo(original numbering;. Treatlncisex I n d H. Heus*el, Experielili?. 9 , ment of IrI with excess deuterium bromide results in incorporation of only one deuterium atom 'moleO F CIiEMISTRY cule proving the presence of a methyl group a t C 9 AL)EPARTXEX'C K D CXEMICAL EVGISEERISC: 17 J . C O R E Y and confirming the presence of a methyl group a t Cs. ~ J N I V E R S I T P OF ILLISOIS J . J . TTRSPRUN:: URBASA,ILLINOIS RECEIVED MAY19, 1955
1-
\.I
YII
YIII
Oxidation of norfriedelendione with alkaline per(.?) To be described in full l a t e r ,
( 6 ) Otherwise t h e P(auiaI)-bromoketone would be epimerizahle, E . J . Corey, i b i d . , 76, 176 (19541 ( 7 ) A n axial bromine i n t h e unit (a) makes a levorotatory contribution whereas t h a t in t h e unit ( b ) , r o m r > - " (i kctirrli,,l: st.ini I .Letate is -T 21i!Ic (>ti (1J) .I
PROOF OF T H E CONSTITUTION O F FRIEDELIN BY MULTI-GROUP REARRANGEMENT OF FRIEDELAN3P-OL TO OLEAN-l3(18)-ENE Sir :
Formula I has been derived for friedelin by the studies described in the previous communication.' This structure bears a most interesting relationship to the three known classes of pentacyclic triterpenes and suggests a biosynthetic pathway starting from a- or B-amyrin which involves a series of consecutive 1,?-shifts of methyl groups and hydrogen (1)
is J C x r y and 1 J 1.rspriiug TAISJ O L R N I I , 77, ,3607 ( l ' l i i )
July 5 , 19.55
3669
COMMUNICATIONS TO THE EDITOR
atoms away from ring A and toward ring E. Consideration of friedelin as a possible rearrangement product of a- or p-amyrin prompted us to undertake the experiments which are outlined $,"dfi3,a~t~:,orc~o in this report and which have led to the direct correlation of friedelin with 6-amyrin.
IX
lupeol (VI)5 into friedelin by a sequence of 1,2shifts would lead not only to the correct carbon skeleton, but also to the experimentally established stereochemical configuration a t all asymmetric centers and to the p-orientation of the hydrogen a t C18 (D/E cis) as in a 6 - and B - a m ~ r i n . ~For this
CH CH3
R = H, Friedelin (V, D / E cis) R = OH, cerin
iriedelin(eno1)
3amy rin
Reduction of friedelin with lithium aluminum reason we favor the view that the hydrogen a t CISin hydride produces friedelan-35-01 (11), m.p. 283.5- friedelin is p-oriented.R 285°,2*3in which the hydroxyl function is axial. If the above biosynthetic pathway is correct, two Treatment of I1 with hydrogen chloride in phenol sequences for formation of pentacyclic triterpenes a t 110" causes a remarkable multi-group rear- follow: (1) lupeol + p-amyrin -+ friedelin and rangement which affords olean-l3(lS)-ene (111) (2) lupeol -+ a-amyrin presently unknown rela(55% yield), m.p. 186-187', [ a ] -~12.5' (C, 0.80, tive of friedelin. We are currently engaged in a chloroform), A,, 213 mb (log E 3.51), bright yellow search for the missing a-amyrin analog of friedelin coloration with tetranitromethane, Anal. Calcd. as well as for other intermediates in both series. for C30Hb0:C, 87.73, H, 12.27. Found: C, 87.76, The formulation of cerin as 26-hydroxy friedelin H, 12.37. This material is identical with an authen- follows from the location of the hydroxyl a t C2 and tic sample prepared from 6-amyrin by oxidation, from the fact t h a t the hydroxyl is very easily acylWOE-Kishner reduction and acid-catalyzed isom- ated or sulfonated (equatorial orientation). erization of the 12,13-double bond to the 13,18-p0I n connection with the work in this and the presition, m.p. 186-1237" (undepressed upon admixture with a sample from rearrangement of freidelan-3p- ceding paper, we wish to express our thanks to Dr. ol), [ a I 2 j -13.9' ~ (C, 0.79, chloroform) bright I. H. Riley for the X-ray measurements, to Dr. R. yellow coloration with tetranitromethane. The in- A. Sneen for the deuterium analyses, to Messrs. frared spectra of the above samples of A13(18)-olefin H. C. Huang, D. F. Joesting and R. G. Schultz for are identicaL4 Further confirmation of identity help in isolation of friedelin and preparation of was obtained by conversion of both products to the intermediates, to the Armstrong Cork Company for same mixture of epimeric oxides with perbenzoic supplies of cork wax and to the Eli Lilly Company acid, m.p. ca. 191-5", undepressed upon admixture. for generous financial support. See L. Ruzicka, A. Eschenmoser a n d H. Heusser, E x p e r i e n l i n , 9 , Both samples of oxide upon treatment with boron 357(5)(1953). trifluoride ethereate yielded olean-1 1, 13(18)-diene (6) E. J. Corey a n d J. J. Ursprung, Chem. and Znd , 1387 (1854). (Iv)4,m.p. 219-220") [ a ] * j D -72.4' (c, 0.95, (7) D. H. R. Barton a n d N. J. Holness, J . Chem. Soc., 78 (1952). (8) This view is confirmed b y a 2-dimenqional F o u t i e r X - r a y analysis chloroform), Amax 242, 250, 260 mp (log E 4.44, 4.50, friedelan-3a-01chloro a n d brornoacetates made in these Laboratories 4.31), A n d . Calcd. for C30H48:C, 88.16, H, on by Dr. I. E. Riley, t h e results of which are completely concordant with 11.84. Found: C, 85.02; H, 11.91,browncoloration structure V ( D / E cis) for friedelin. These results will be reported later. with tetranitromethane, mixture m.p. undepressed. DEPARTMENT OF CHEMISTRY --f
IX
I1
X
111
CHEMICAL ENCINEERISC E. J . COREY OF ILLINOIS J. J. URSPRUNC UNIVERSITY URBANA,ILLINOIS RECEIVED MAY 19, 1955 AND
LUMINESCENCE SPECTROSCOPY OF PORPHYRINLIKE MOLECULES INCLUDING T H E CHLOROPHYLLSI
The conversion of I1 into I11 proves the location of methyl groups a t C1, and CZO as in P-amyrin and, together with the degradative work, establishes beyond any doubt structure V for friedelin, which is complete except for the orientation of the hydrogen a t Cis. The biosynthetic pathway for the conversion of
Sir: The understanding of the participation of the chlorophylls in the primary reaction of photosynthesis demands an exact knowledge of the location and characteristics of the lowest excited states of these molecules.2
(2) J. J. Lander a n d W. J. Svirbely, THISJOURNAL, 66, 235 (1944). (3) Recently isolated from various natural sources b y P. R . Jefferies, J. Chcm. Soc., 473 (1954). a n d b y T. Bruun, Acta Chcm. Scond., 8 , 71 (1954). (4) K. T a k e d a , J . Pharm. SOC.J a f i a n , 63, 197 (1943); C. A , , 45 586 (1951).
(1) Work done under a contract between t h e Office of Naval Research, U. s. N a v y , a n d t h e Florida S t a t e University. (2) R . S. Becker a n d M. Kasha, "Luminescence Spectroscopy of Molecules a n d t h e Photosynthetic System,'' Conference on Luminescence, Pacific Grove, California, M a r c h 29, 1954, National Research Council Bulletin, in press.
