July 3, lO(i2
COMMUNICATIONS TO THE EDITOR
assignment of this rests on analogy to the previous case. In vitro biological data on the 6-deoxy epimers (Ia, Ib) as well as on known 6-deoxy-6-demethylt e t r a c y ~ l i n e ~(IC, . ~ ~a~ compound with no asymmetry a t C.6) are presented in Table I.I5 The TABLE I Bioassayo us.
Compound
2G4T TABLE I
70Composition 1' 2b 3c Butene-1 5 3.6 23.4 trans-Butene-2 67 66.5 38.6 cis-Butene-2 28 29.5 35.6 Methylcyclopropane 0 5 0 4 2.4 b This work, pyrolysis a Friedman and Shechter (ref. 2). at -160'. This work, photolysis (3130 A,).
K. Pnt-irmoniaeb
initially formed excited olefins, photolyses were carried out in the presence of added nitrogen, a t a-6-Deoxytetracycline ( I a ) pressures up to 2 atmospheres, without changing a-6-Deoxy-5-hydroxytetracycline(Ib) 1100 the ratios of the products. Thus the compositions P-6-Deoxytetracycline ( Ia) 500 shown in the table represent the inifid rearrange6-6.Deoxy-5-hydroxytetracycline ( I b ) 400 ment ratios from the photolytically produced cara Expressed in oxytetracycline units/mg. Cf.R . C. Ker- bene. Below 50 mm. some small variations in the sey, J . Ant. Pharm. Assocn., 39, 252 (1950). In this assay product ratios were observed, which could be ration5-hydroxytetracycline is taken as the standard a t 1000 alized in terms of the secondary isomerization of units/mg. Similar relative activities have been noted with other microorganisms. the methylcyclopropane (initially formed with excess energy) to butenes. At 4 mm. the yield of reduced activity in the p-series may well be the methylcyclopropane had fallen to l.O%, the yield result of conformational distortion. of trans-butene-2 had risen to 42y0 and a trace of (1.5) We are indebted t o Mr. J. J. Smith and his asqociates for these isobutene was detected. data. The relatively high proportion of butene-1 and M. SCHACH VON ~ ' I T T E N A U methylcyclopropane, and the near equivalence of MEDICALRESEARCH LABORATORIES JOHN J. BEEREBOOM ROBERTK. BLACKWOODthe amounts of cis- and trans-butene-2 in the photoCHAS.PFIZER& Co., INC. GROTON,CONNECTICUT CHARLESR. STEPHENSlytic decomposition are in striking contrast to those from the pyrolyses. These differences are RECEIVED M A Y24, 1962 most reasonably explained by postulating that the carbene produced photochemically is vibrationally HOT RADICAL EFFECTS IN AN excited. The results, therefore, indicate a hot INTRAMOLECULAR INSERTION REACTION radical effect in intramolecular insertion reactions Sir : of carbenes previously only noted in intermolecular Thermal decomposition of p-toluenesulfonyl- reactions. hydrazones of aldehydes and ketones in basic (4) H. hl. Frey, ibid, 80, 5005 (1958). media gives rise to diazocompounds, which in H. M. FREY DEPARTYEST OF CHEMISTRY aprotic solvents themselves undergo decomposition THE I. D. R. STEVENS UNIVERSITY by a carbenoid process. The decomposition of the SOUTHAMPTON, ENGLAND RECEIVED APRIL 14, 1962 tosylhydrazone of %butanone' in diethylcarbitol in the presence of sodium methoxide yields cisand trans-butene-2, butene-1 and a trace of AN ISOTOPE EFFECT DURING THE methylcyclopropane (see table). These comCOUNTERCURRENT DISTRIBUTION OF pounds presumably are formed from methylethylARABINOSE- 1-C carbene by reactions that can be considered as Sir : intramolecular insertion reactions formally similar Insofar as we know, the literature lacks any to the intermolecular insertion reactions of methyl- reference to an isotope effect influenced by the ene itself ,;{ position of C14in a sugar-or other solute-under\Ye wish t o report t h a t the thermal decompo- going countercurrent distribution. For this reason, sition of methylethyldiazirine in the gas phase a t we wish to report the data below. 160' also results in the formation of these hydro~-Arabinose-l-Cl~( K = 0.11) moved more carbons in ratios virtually identical with those slowly than unlabeled D-arabinose (Fig. 1) during reported by Friedman and Shechter.? There can countercurrent distribution in cyclohexane-95% be little doubt that this reaction proceeds zlia the ethanol with the result t h a t specific activity deformation of the carbene which supports a similar creased with increasing number of the tubes of the mechanism for the decomposition of the tosyl- train constituting the sugar zone. D-Arabinosehydrazpnes. Photolysis of methylethyldiazirine l-C14 and unlabeled L-arabinose also were partly (3130 A. radiation) also results in the formation of resolved (Fig. 2 ) ; similarly ~-arabinose-l-C'~ and the same C I H s hydrocarbons but in quite different unlabeled D-arabinose were partly separated. I n ratios. all cases, such plots of log specific activity against In the photolyses the relative yields of the prod- fraction number for tubes containing this pentose ucts were independent of the pressure of the diazi- were linear and were never parallel to the abscissa, rine in the range 50 to 200 mm. To eliminate the an index of resolution.1 When radioactivity possibility of secondary isomerization of the resided on carbon 5 , the mobi!ities of the radio(1) J W. Powell and M. C . Whiting, Tetrahedron, 7, 30.5 (1959). active and unlabeled D-arabinose were indis( 2 ) L. Friedman and H. Shechter, J. A m . Chem. SOL.,81, 5512 tinguishable, after 350 or 800 transfers. Neither (1939). D-xy10se-l-C'~ ( K = 0.26) nor ~ - r i b o s e - l - C '(~K (3) W. E. Doering, R . G. Buttery, R. C. Laughlin and S . Chaud6-Ditr~etliyl-6-deoxytetracycline(IC)
900 700
-
huri, ibid., 78, 3224 (1956).
(1) K . A . Piez and H. Eagle, J. A m . Chem. SOL.,78, 5284 (1956).
