May 5 , 1902
COMMUNICATIONS TO THE EDITOR
Fermentation of strophanthidin by the general procedure previously described, with Nocardia restrictus, produced two principal transformation products. Paper chromatography* revealed that both were less polar than strophanthidin. Separation was effected by chromatography upon silica gel and fractional crystallization. The product with higher Rfwas characterized as the anhydrostrophanthidone II.133T h e second product was a new phenolic compound (III), m.p. 263-265' dec., [ o 1 I z 7 ~+'iso ( c 0.76, pyr.) ; A&. 217 mp ( E 25,600), 2S0 mp ( E 2,200); '::A; 2 88 p , 3.03 p j 5.77 p , 6.22 p , 6.30 p , G.68 p . 4 Acetylation of 111 yielded a monoacetate, m.p. 206-20s0, [cy]*'D +6G0 (c 0.70, chf.); "::A: 215 mp ( E 22,100), 2 G i mp ( E 680), 275 mp ( E 6-10); 2 SS p ; 5.60 p , 5.72 p , 6.15 p , (3.30 p , 6.70 p. Catalytic hydrogenation of I11 with platinum (hydrogen consumption: 1 mole equivalent) yielded the dihydro derivative V, characterized by direct comparison with a
1753
formations. Work is currently under way to evaluate the hypothesis that biological conversion of I1 to I11 may proceed via AI-dehydrogenation to a 19-0xo-D~~~-dienone and then aromatization accompanied by liberation of a C1 unit.' This work was supported by grants from the Research Committee of the Graduate School from funds supplied by the Wisconsin Alumni Research Foundation. (7) Formaldehyde has recently been identified as appearing in stoichiometric ratio t o estrune after placental micrusomal aromatization of A'-androstenedione and 19-hydroxyandrostenedione ( H . Breuer and P. Grill, Z . physiol. Chenz., 324, 254 (1861)). However, in view of t h e facile biological interconversion of formaldehyde and formic acid (6. F. R I . Huennekens and 11.J . Osborn, Ado. iii Enzymology, 21, 369 (1969)), it i s possible t h a t t h e formaldehyde m a y have arisen b y teduction of a formic acid-equivalent.
DEPARTMENTS OF PHARMACEUTICAL S. MORRISKUPCHAN CHEMISTRY A N D PHARMACOGSOSY CHARLES J. SIH UNIVERSITY OF ~ ' I S C O S S I N K . KATSUI MADISOS6, WISCOSSIS 0. EL TAYEB RECEIVED FEBRUARY 24, 1962
SYNTHESIS OF BORON NITRIDE
Sir: A broad resemblance of boron nitride to carbon
sample prepared from dihydrostrophanthidin by the procedure of Turner and Xeschino.6 Catalytic oxidation of I in the presence of platinum and oxygen, followed directly by treatment with alkali a t Uo, yielded the 19-noranhydrostrophanthidone IV, m.p. 240-241°, [ c Y ] * ~ D+33' (c 2.67, chf.); A$:, 2.85 p , 5.130 p , 5.72 p 6.01 p , 6.15 p ; AEt,"," 230 mp ( E 24,700). Dehydrogenation of I V over palladium black in refluxing ethanol gave phenol 111. When anhydrostrophanthidone I1 was exposed to ,V.restrictus, a rapid and high-yield conversion to phenol 111 was observed. Fermentation of the 19noranhydrostrophanthidone IV under the same conditions resulted in exceedingly slow conversion to phenol 111. These findings are in good agreement with the recent studies of Morato, et ~ l . on the biosynthesis of estrogens from androgens with human placental microsomes. The latter authors' observations support the sequence A4androstenedione + 19-hydroxyandrostenedione + 19-oxo-androstenedione -+. . . ' > estrone for the steps in biological estrogen formation. Furthermore, i t was found t h a t 19-norandrostenedione was a poor substrate for estrogen formation. The parallel findings in the respective studies that the 19-nor-steroids are less effective phenol-precursors than the corresponding 19-oxo-steroids suggest that the stepwise sequence may be similar for the microbiological and placental microsomal trans(2) H. R . Urscheler, Ch. T a m m a n d T. Reichstein, Hrlu. C h i m . A d a , 38, 897 (1955). ( 3 ) A . K a t z , ibid., 40, 831 (1937). (4) Satisfactory analytical d a t a were obtained for t h e new compounds reported herein. ( 5 ) R . B. T u r n e r and J. A. hleschino, J . A m . Chem. Soc., 80, 4862 (1938). (6) T . hlorato, M. H a y a n o , R . I. Ilorfman and I,. R. Axelrod, Hiorhviri B i o p h y s . Res. Coinm., 6, 334 (1961).
in its various structural forms,'J combined with certain physical characteristics, makes boron nitride a material of considerable theoretical interest and of growing importance in nuclear, refractory, electrical and lubrication technologies. M'hile the synthesis of boron nitride has been studied fairly e~tensively,3,~-* current synthetic methods are beset with considerable technical difficulties. Xccordingly, a straightforward synthesis adaptable to laboratory or large-scale production of boron nitride is of interest. Orthoboric acid (1 mole) and urea ( 2 moles) are mixed and gradually heated. At about GOo the reactants melt with the evolution of water which is removed from the system in a stream of nitrogen or, preferably, under reduced pressure. As water is removed, the initially limpid liquid residue increases in viscosity and sets to a glass. Above about 165' (subsequent heating is most conveniently effected in a nitrogen stream) the glass , undergoes ~ decomposition, evolving a volatile sublimate and leaving a white, cinder-like residue (residue a t GOOo is lS.45 wt. 70urea and boric acid reactants.
