1452 Anal. Calcd for CI?HlaOa: C, 64.85; H, 6.35. Found: C, of alcohols was oxidized with chromium trioxide as in the prepara64.84; H, 6.16. tion of ketone 10 to yield 11 mg (69 %) of crude ketone 32. Analy(b) A solution of pentacycIo[4.4.0.O2~4.O3~8 .05,7]deca-9-ene(28, sis of the crude compound by glpc showed it to be 9 0 % of one 100 mg, 0.77 mmol) in 30 ml of ethyl acetate was treated with a ketone. A small amount of the ketone was purified by preparative 2 0 z excess of ozone at -70". The crude ozonide, after removal glpc; ir (CCla) 1770 cm-'; mass spectrum, m/e 132 (M+), 104 of the ethyl acetate by evaporation, was oxidized at 0" with Jones (M - CO). reagent." The crude reaction mixture was diluted with 3 Nsodium endo,erzdo-3,7-Dicarbomethoxytetracyclo[3.3.O.O*~~.O4~6]oc~ne hydroxide and extracted with ether. The aqueous solution was (33). (a) A solution of endqendo-secocubane dimethyl ester 19 acidified with 10% hydrochloric acid and extracted three times with (290 mg, 1.3 mmol), 3.0 g of silver nitrate, 20 ml of water, and 25 ether. The acidic ether extracts were dried, concentrated by asml of methanol were refluxed under nitrogen for 2 days. The pirator pressure, and treated with excess diazomethane. The 120 reaction mixture was cooled and diluted with 100 ml of ether. mg of yellow oil obtained was examined by glpc and found to conThe water layer was drawn off and the ether solution dried. tain one volatile product ( 3 0 z yield from olefin 28 according to The solvent was removed by evaporation to give 194 mg (66%) of glpc estimates). A sample of this product was purified by preparadiester 33: mp 87-88'; ir (CCI,) 2935, 1735 cm-l; nmr (7,CC1,) tive glpc and found to have the same infrared spectrum, mass 6.40 (6 H , s), 6.90 (2 H , quintet, J = 2.2 Hz), 8.15 (6 H, m); mass spectrum, and glpc retention time as the material from part a. spectrum, mle 222.
Aliphatic Semidiones. XV. Bicyclo [n. 1.O] alkanes'
2,3-Semidiones Derived from the
Glen A. Russell,* John J. McDonnell, Philip R. Whittle,2 R. S. given^,^ and R. G. Keske4 Contribution from the Department of Chemistry, Iowa State University, Ames, Iowa 50010. Received M a y 29, 1970 Abstract: T h e synthesis of bicyclo[2.1 .O]pentane-, bicyclo[3.1 .O]hexane-, bicyclo[4.1 .O]heptane-, bicyclo[5.1 .O]octane-, a n d bicyclo[6.1 .O]nonane-2,3-semidioneshas been investigated. Acyloin condensations of cis-l,2-cyclopropanedicarboxylic esters failed t o yield bicyclopentane semidiones. Instead, t h e ring-opened cyclopentanesemidiones were formed. Acyloin condensation or oxidation of the 2- o r 3-ketones i n basic solution produced t h e bicyclo[3.1 .O]hexane-2,3-semidione. T h e hyperfine splittings observed i n t h e esr spectrum were assigned t o the six hydrogen a t o m s by examination of a n u m b e r of deuterium a n d alkyl derivatives. Extended Huckel self-consistent field calculations a r e reported which a r e i n excellent agreement with t h e experimentally observed values. During this investigation it was determined t h a t t h e a-methylene g r o u p i n bicyclo[3.l.0]hexanesemidione underwent a highly stereoselective hydrogen-deuterium exchange i n basic dimethyl sulfoxide solution wherein the exo hydrogen exchsnged m u c h m o r e rapidly t h a n the e n d o hydrogen. I t was also observed t h a t syn-6-alkylbicyc10[3.1.0]hexane-2,3-semidiones rearranged t o the a n t i isomers with base catalysis. An electrocyclic mechanism is suggested i n which the bicyclo[3.1 .O]hexane ring opens t o a cyclohexadienyl intermediate which undergoes competing ring closure and aromatization. Overoxidation of the bicyclo[3.1 .O]hexanesemidione leads t o a n o-semiquinone with molecular rearrangement i n which C-6 of t h e bicyclic semidione is converted t o C-3 i n the semiquinone. A sigmatropic 1,4 migration followed by a cyclopropanol ring opening is suggested. A variety of tricyclic derivatives containing t h e bicyclo[3.l.0]hexanesemidione nucleus a n d showing interesting long-range esr splittings have been synthesized. Bicyclo[4.1 .O]heptane-2,3-semidione appears t o exist in two conformations depending u p o n the substitution pattern. T h e importance of long-range interactions is greatly reduced i n the bicyclo[4.1 .O]heptane SYSt e m a n d inconsequential i n the bicyclo[5.1 .O]octane- a n d bicyclo[6.1 .O]nonane-2,3-semidiones.
t t e m p t s to prepare b i c y c l o p e n t a n e s e m i d i o n e (1) b y a c y l o i n c o n d e n s a t i o n o f the c i s - c y c l o p r o p a n e d i c a r b o x y l i c e s t e r i n the p r e s e n c e or absence o f t r i m e t h y l c h l o r o s i l a n e l e d instead to c y c l o p e n t a n e s e m i d i o n e , detected b y esr s p e c t r o s c o p y (Scheme I).
A
Scheme I
CO,Et
0.
NaK, CH30CH2CH20CH3 Me,SiCI
R i n g opening is not s u r p r i s i n g s i n c e the enediol d e r i v a t i v e r e s u l t i n g f r o m the a c y l o i n c o n d e n s a t i o n would be a b i c y c l o p e n t e n e d e r i v a t i v e . R i n g opening c o u l d o c c u r by h y d r o g e n a t i o n with h y d r o g e n released f r o m traces of h y d r o x y l i c i m p u r i t i e s . A l t e r n a t e l y d i s y m metric r i n g opening (not a l l o w e d b y o r b i t a l s y m m e t r y c o n s i d e r a t i o n s ) m i g h t precede the g a i n o f t h e t w o h y d r o g e n atoms ( S c h e m e 11). R i n g o p e n i n g a l s o oc-
mu-ao-=
Scheme I1
h-
0-
n-
(1) Application of Electron Spin Resonance Spectroscopy to Problems of Structure and Conformation. XX. Supported by the Army Office of Research (Durham) and by the National Science Foundation. (2) National Aeronautics and Space Agency Predoctoral Fellow, 1965-1968; Petroleum Research Fund Fellow, 1968-1969. (3) National Institute of Health Postdoctoral Fellow, 1966-1967. (4) National Science Foundation Predoctoral Fellow, 1967-1969.
Journal of the American Chemical Society
93:6
1 March
24, 1971
\
0-
1
u
1453 Table I.
Hyperfine Splitting Constants and Assignments for Substituted Bicyclo[3.l.0]hexane-2,3-semidionesat 25 O in DMSO Solution
Substituent
a,H
None, 6a-c sy/2-6-D, 76 6,6-Dideuterio, Sb
4.0 4.0 4.0
6,6-Dimethyl, g b ~/!ti-6-CH3,loh sy/1-6-CH3,1 l b aiili-6-C2Hb112b arzri-6-C2Hi-l-D, 13b
5.1 4.3 4.6 4.2 alD = 0.7 4.2
a~i-6-Methoxymethy1,
a4-endoH
ad-exoH
a4-exoD
ast1
aesynH
7.9 7.9 7.9
14.9 14.9 14.9
2.3
0.8 0.8 0.8
0.8
Other
aB-antiH
4.0 4.0 aD
=
0.7 0.9 0.40 1.1 0.35 0.35
7.6 7.6 7.4 7.8 7.8
14.6 14.6 14.3 14.6 14.7
2.3 2.3
7.8
14.7
0.35
7.8 7.6 8.2 7.6
14.6 14.2 14.5 14.3 13.85
0.8
2.3 2.3
=
UB~-CHS
0.90
U B ~ - C H= ~
0.45 0.40
1.5 = 0.75
a6a-CH2
aBa-c~2= 0 . 7 5 a6a-CH~
= 0.75
14c
1-Methyl, U b 5-Methyl, 16b 5-Isopropyl, 17b l-C*Ha-5-CH3, lSb l-Isopropyl-4-e/ido-CH3, 19* l-Isopropyl-4-exo-CH3,
3.8 4.0
0.8
0.58
0.7
4.2 3.8 3.7 4.4 4.9
0.58
0.8
4.2
0.58
0.8
4.2
0.4
0.4
4.9
0.8
0.8
4.0
0.7 0.7
4.4 4.4 4.6
0.7 2.2
6.2
~ C H
