1694 J. Org. Chem., Vol. 40, No. 12, 1975
McDonald, Steppel, and Cousins
All kinetic runs were made with 1.0 X M ROTs (RONs) and 1.2 X M potassium acetate. Infinity (10t1/2) titers of these solutions gave the following percent reaction: 1-OTs (loo'), 94.2%: 1-ONs (SO'), 97.3%; 1-ONs (loo'), 97.8%. All preparative scale buffered acetolyses were determined using 0.010 M ROTs and 0.012 M potassium acetate. The solutions were sealed in flasks and placed in the constant-temperature bath for the allotted time. After removal from the bath and quenching in ice-water, the contents were poured from the flasks into water and extracted with methylene chloride which was washed with water, 5% aqueous NaHC03, and water and dried (NaZS04). Evaporation of the solvent and chromatography of the residue then gave the products.
Acknowledgments. The authors thank the National Science Foundation (GP-10691) for support of this research and for matching funds to purchase the NMR and mass spectrometers. Registry No.-1-OH, 54798-03-7; 1-OTs, 54798-04-8; 1-ONs, 54798-05-9; 1-OAc, 54798-06-0; 1-OAc 1,3,5-trinitrobenzene complex, 54798-07-1; 2, 3806-02-8; 3, 36044-40-3; 4, 54832-62-1; 5, 54798-08-2; 6, 54522-71-3; 6 1,3,5-trinitrobenzene complex, 5479809-3; 7, 54798-10-6; 8, 54798-11-7; 10, 54798-12-8; 11, 54798-13-9; 12, 53477-10-4; 12 1,3,5-trinitrobenzene complex, 54798-14-0; ethyl cyanoacetate, 105-56-6; 2-chlorotropone, 3839-48-3; 2-chloroazulene, 36044-31-2; 2-chloro-l-trifluoroacetylazulene,54798-15-1; methyl 2-chloro-l-azulenecarboxylate, 54798-16-2; 2-chloro-1-azuloic acid, 54798-17-3; p-nitrobenzenesulfonyl chloride, 98-74-8; tosyl chloride, 98-59-9.
References and Notes (1) Part X: R. N. McDonald. H. E. Petty, N. L. Woife, and J. V. Paukstelis, J. Org. Cbem., 39, 1877 (1974).
(2) R. N. McDonald and J. R. Curtis, J. Am. Cbem. SOC.,93, 2530 (1971). (3) See C. J. Lancelot, D. J. Cram, and P. v. R. Schleyer in "Carbonium Ions", Voi. 3, G. A. Olah and P. v. R. Schleyer, Ed., Wiley-interscience, New York, N.Y., 1972, for a review on this general topic. (4) R. N. McDonald, N. L. Wolfe, and H. E. Petty, J. Org. Chem., 38, 1106 (1973). (5) See R. N. McDonald and R. R. Reitz, J. Org. Cbem., 37, 2703 (1972), for the pKa's of the I-, 2-, 5-, and 6-azuloic acids. (6) 2-Chlorotropone was pre ared by the sequence tropllidene tropyiium BF4ditropyl etherPbxc t r o p ~ n e ' ~ . ~2-chlorotr0pone.~~~~ (7) (a) K. Conrow, Org. Syntb., 43, 101 (1963); (b) H. E. Petty, Ph.D. Thesis, Kansas State University, Manhattan, Kans., 1971; (c) A. P. Ter Borg, R. Van Heiden, and A. F. Bickei, Recl. Trav. Cbim. Pays-Bas, 81, 177 (1962). (8) T. Nozoe. S.Seto, S.Matsumura, and Y. Murase, Bull. Cbem. SOC.Jpn., 35, 1179 (1962). (9) T. Nozoe, S.Seto, S.Matsumura, and Y. Murase, Bull. Cbem. SOC.Jpn., 35, 1990 (1962). (IO) P. D. G. Dean, J. Cbem. SOC.,6655 (1965). (11) For those wishing to prepare I O , a more convenient route via the methyl esters could use methyl cyanoacetate in the original reaction with 2chiorotropone leading to the dimethyl ester corresponding to 2. (12) A. G. Anderson and R. G. Anderson, J. Org. Chem., 27, 3578 (1962). (13) J. R. Curtis, Ph.D. Thesis, Kansas State University, Manhattan, Kans., 1971. (14) R. N. McDonald and G. E. Davis, J. Org. Cbem., 38, 138 (1972). (15) Available from R-M Research Products, inc., Manhattan, Kans. 66502. The small (3 ml) working volume of this conductance ceii and the ability to work at elevated temperatures with this made these studies possible. (16) E. Heilbronner in "Non-Benzenoid Aromatic Compounds", D. Ginsburg, Ed., Interscience, New York, N.Y., 1959, p 200. (17) S. Winstein, P. E. Klinedinst, and G. C. Robinson. J. Am. Cbem. SOC., 83, 885 (1961): E. F. Jenny and S.Winstein, Helv. Cbim. Acta, 41, 807 (1958). (16) Footnote 21 in ref 2. (19) Melting points were determined on a Kofler hot stage and are uncorrected. Spectra were determined with commercial instruments (ir, PerkinElmer 137; NMR, Varian A-60 and T-60; uv-visible, Cary 11; mass, AEiMS9). NMR spectral data are listed as centers except for multiplets, where the range of the signals is given.
-
-+
+
-+
Molecular Rearrangements. XIL1" Reactions of 2-Chlorobicyclo[ 2.2.lIhept-2-ene exo-Oxide and 2-Chlorobicyclo[2.2.2]oct-2-ene Oxide with Lithium Diethylamide Richard N. McDonald,* Richard N. Steppel,lb and Raymond C. CousinslC Department of Chemistry, Kansas State University, Manhattan, Kansas 66506 Received January 15,1975 The reactions of two bicyclic a-chloro epoxides, 2-chlorobicyclo[2,2.l]hept-2-ene ero-oxide (2) and 2-chlorobicyclo[2.2.2]oct-2-ene oxide (3), with lithium diethylamide have been investigated. With 2, refluxing benzeneether and ether (0 to -15') were examined as solvents while, with 3, only refluxing benzene-ether was studied. From 2 the major product was tricycl0[2.2.1.O~~~]heptan-3-one (4). The amount of the minor product, tricyclo( 5 ) , was solvent and base concentration dependent. Using 2-3-d in ether, no deuterium was [2.2.1.02~6]heptan-3-ol found in 4 and none a t Cs of 5. While the formation of 4 can be readily rationalized as involving transannular insertion by the a-keto carbene formed by CY elimination a t CBof 2, the pathway 2 + 5 is unclear. From 3, two major (15) and N,N-diethylbicyclo[2.2.l.]heptane-7-carboxamide (161, and two products, tricyclo[3.2.1.02~7]octan-6-one minor products, 3-chlorobicyclo[2.2.2]octan-2-one(13) and bicyclo[2.2.2]octanone (14), were isolated. Ketone 15 and amide 16 are believed derived from the a-keto carbene, 15 by transannular insertion and 16 by Wolff ring contraction, while ketones 13 and 14 probably arise via thermal rearrangement of 3. These results are compared with those from other methods of generating the respective bicyclic a-keto carbenes or carbenoids. The site specificity in these conversions of bicyclic a-chloro epoxides 2 and 3 to tricyclic ketones 4 and 15, respectively, may prove synthetically useful.
The reactions of strong bases with acyclic, cyclic, and bicyclic epoxides have been studied by a number of researchers,2 notably Cope, Crandall, and Rickborn. The major types of processes observed were a elimination (yielding insertion and ketone products), @ elimination, and nucleophilic epoxide ring opening. The extent of involvement of these processes was dependent on structural effects in both the epoxide and the base.
Our interests in the chemistry of a-chloro epoxidesl~~ led us to consider how the a-chloro substituent might effect the outcome of such strong base reactions, Using ( 2 ) - 2 chlorobutene oxide (1) as an example, the conceivable pathways are listed in Scheme I. Nouri-Bimorghi4 reported that varying amounts of /3 elimination (pathway a) and nucleophilic epoxide ring opening (pathway e) were observed when three acyclic a-chloro epoxides were allowed to react
J. Org. Chem., Vol. 40, No. 12,1975 1695
Reactions of Bicyclic a-Chloro Epoxides with LiNEt2
Scheme I
(8), 12% exo -3-chlorobicyclo[2.2.1] heptan-ero -2-01 (9), 11% 7, and 14% endo-3-chlorobicyclo[2.2.l]heptan-2-one(10).
OH
I
CHgClCHCH3
0
I Nu
LiNEt
II
CH3CCH=CH2
and/or 0 Nu
e
Et,O
a f
\
0
/
7
II I
A
CHF-CHCH3 1
2
I
J."
and/or OH
0
I
II
rJ
1
Since we had previously shown that 4 is reduced to a mixture of 4 and 5 under these reaction conditions (albeit under reflux for 4 days), the formation of 8 and 9 from 7 is J CH,CCH=CH; rationalized by carbonyl reduction of 7 to 9 (or its C2 epimO=C=C(CHJ, er) followed by dehydrochlorination. Formation of amide 6 from 2 and lithium diethylamide with phenyllithium. As expected, the extent of involvement can be considered to arise by attack of the base on the carof these pathways was dependent on the substrate strucbonyl of exo-2-chlorobicyclo[2.2.l]heptan-7-one, a major ture. product in the neat, thermal rearrangement of 2.1,6GeneraFor the present study, we wished to limit the probable tion of the amide group carbonyl, C1-C7 bond cleavage, and reaction pathways given in Scheme I to c, which would enloss of chloride ion from CZwould yield 6. able us to evaluate it as a method of accomplishing WolffIn an effort to shorten the reaction time of 2 with lithium type rearrangements via a-keto carbenes (or carbenoids). diethylamide, to obtain complete reaction, and to study the Such should be possible using certain bicyclic a-chloro epeffect of solvents on this process, we examined several benoxides where pathways a, b, d, and e should be disfavored, zene-ether mixtures as well as ether as solvents. In short, as should the eqilibrium shown between a-keto carbene the benzene-ether mixtures gave nonreproducible results. and oxirene structure^.^ The a-chloro bicyclic epoxides In refluxing either with 1.1 equiv of lithium diethylamchosen were 2-chlorobicyclo[2.2.l]hept-2-eneexo-oxide1!6 ide, the product derived from 2 was found to contain 10%8. (2) and 2-chlorobicyclo[2.2.2]oct-2-eneoxide7 (3), since we Thus it appeared that thermal rearrangement of 2 7 folhad previously studied their neat, thermal, and certain catlowed by reduction was a competing process under these alyzed rearrangements, and Crandal122j had reported on conditions. The amount of 8 could be lowered to
