Dec. 20, 1955
COMMUNICATIONS TO THE EDITOR
+60.0° (benzene); Found: C, 58.7; H, 5.7; N, 8.0. The racemate, formed by recrystallization of a mixture of equal quantities of I11 and I V from benzene-methanol, melted a t 264-265". Partial hydrolysis of I11 with sodium hydroxide in aqueous dioxane yielded (-)-menthyl hydrogen 2,6,2',6'tetranitro-4,4'-diphenate (V) , m .p. 216-2 18O , [a] lD -38.6" (acetic acid); Found: N, 9.7, 9.5; neut. eq. 562. Treatment of V with thionyl chloride, followed by addition of (-)-menthol in pyridine, gave I11 (m.p., mixed m.p., [ a ] ~ )Similar . treatment of the acid chloride of V with (+)-menthol afforded I, m.p. 247-248.5' (Found: C, 58.4; H, 6.3; N,8.1). The optical activity of I was zero, as measured in pyridine and benzene solutions a t 589, 578, 546 and 435 mp.
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and IV solvolyzed a t closely similar rates and showed one-fourth the logarithmic rate reduction of the tetradeutero derivative. TABLE I ACETOLYSIS RATESOF DEUTEROCYCLOPENTYL TOSYLATES Tosylate of
lO5k (sec.-')(l 50'
A A F =k (per D) cal./mol'e
Cyclopentanol 4.21 .. trens-Cyclopentanol-2-d 3.62 99 cis-Cyclopentanol-2-d 3.47 125 Cyclopentano1-2,2,5,5-d( 2.05 116 a 0.1Msolutions in acetic acid, 0.117M in sodium acetate. Rates were run in duplicate; reproducibility was 1%.
The results are clearly inconsistent with a common interpretation of resonance structures such as WM. H. NICHOLSCHEMICAL LABORATORY 11. The results are completely consistent with a NEW YORKUNIVERSITY KURTMISLOW RICHARDBOLSTAD molecular orbital viewpoint formulated as in Fig. 1. NEW YORK53, N. Y . RECEIVEDOCTOBER 14, 1955
THE STEREOCHEMISTRY OF HYPERCONJUGATION
Sir: The most important recent evidence for the concept of hyperconjugation has been the finding of decreased reactivity in solvolytic reactions of tertiary halides and secondary sulfonates in which 0hydrogen atoms are substituted by deuterium. The accepted explanation has involved the de11) creased effectiveness of hyperconjugation (I because of the greater strength of the carbon-ieuW terium bond. Changes in inductive effect are not 01 s involved for H D has no dipole moment. The imFig. 1.-Transition state of a solvolytic reaction of plied analogy between hyperconjugation and elimination reactions' and the suggested importance of cyclopentyl tosylate illustrating a molecular orbital viewthe trans-hydrogen in 113have been scrutinized by point of hyperconjugation. a study of the stereospecificity of the deuterium The sp3hybrid orbitals of the P-C-H bonds are not isotope effect. orthogonal to the developing p orbital a t the reac6+ 6tive center; consequently, overlapping will occur. H-CRt-CRz. . . .X t)H' CR*=CRz X A molecular orbital of the proper symmetry may I I1 be constructed from the methylene hydrogen atoms Reaction of cyclopentene oxide with lithium alu- which, by overlapping with the component p orminum deuteride gave trans-cyclopentanol-2-d (111) bital of the P-carbon, forms a conjugated system containing 0.98 f 0.03 atom of D per molecule, with the developing p orbital formally analogous which was converted to the tosylate, m.p. 28-29', to that in an allyl carbonium ion. Because the two and displaced by tetramethylammonium acetate in methylene hydrogens are acting as a unit in a molecpure acetone to afford, after hydrolysis, cis-cyclo- ular orbital, substitution of either one by deuterium pentanol-2-d (IV). The infrared spectra of I11 will have the same efect on the energy of Ihe pseudo-a and I V were different in many respects and demon- bond, to a close approximation. strated that each deuteroalcohol was free from its DEPARTMENT OF CHEMISTRY AND epimer. CHEMICAL ENGINEERING ANDREWSTREITWIESER, JR. Ten exchanges of cyclopentanone with excess UNIVERSITY OF CALIFORNIA ROBERT H. JAGOW 4, CALIF. SHIGETO SUZUKI weakly basic deuterium oxide gave cyclopentanone- BERKELEY RECEIVED OCTOBER 15, 1955 2,2,5,5-d4, which was reduced with lithium aluminum hydride a t -80" to cyclopentanol-2,2,5,5-d4 (V) containing 4.1 f 0.1 atoms of D per molecule. THE CARCINOSTATIC ACTMTY OF SOME 2-AMINOThe tosylate had m.p. 28-29'. 193,4-THIADIAZOLES The acetolysis rates were determined a t 50' for Sir: the tosylates of 111, IV, V and cyclopentanol (Table During screening of compounds for their carcinoI). There is no important stereochemical effect static activity, several 2-amino-1,3,4-thiadiazole for deuterium substitution. The tosylates of I11 derivatives were found to be active against several (1) V. J. Shiner, Jr., THISJOURNAL, 7 6 , 2925 (1953); 76, 1603 transplanted animal tumors. A representative (1954). group of the derivatives and analogs synthesized (2) E. S. Lewis and C. E. Boozer, ibid., 76, 791 (1954). and tested are listed, along with the results ob(3) G. Baddeley, A n n . Refits. o n Progress Chem. (Chem. SOC. London), 61, 169 (1954). tained, in Table I. The synthesis of these particu-
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