COMMUNICATIONS TO THE EDITOR
6150
Vol. 80
THE PHOTODIMER OF Z16-DIMETWLPPYRONE sir:
118-120°, A,"f 2.89, 3.05 p ( a d . Found: C, G.74; HI 8.18; C-CHX, 17.5), identilied as VI Recent interest in the ultraviolet irradiation of since it reacted with 3.9 equivalents of sodium ab-unsaturated carbonyl compounds1 prompts us periodate with the production of 3.8 equivalents of to report on an investigation of the dimer obtained acid6 and gave a dibenzoate (VII), m.p.x 151-153', ' :A: 2.89, 3.01, 5.81 p (anal. Found: C, 67.23; by irradiation of 2,6-dimethyl-4-pyrone. The solid pyrone was irradiated to give the H, 5.76), which failed to react with sodium periodate. Hydrolysis of IV gave an unsaturated dimerI2 m.p.a 281-284' dec.,: ' ::A: 5.88 p, 233 mp (E 6,600) anal. Found: C,67.54; H, 6.42), acid which on hydrogenation yielded a saturated 3.02, 3.20, 5.86 p, no which formed a bis-2,4-dinitrophenylhydrazone, acid, m.p. 114-116°, : : :A dec. ca. 300°, Afg 3.05, 6.20, 6.30 p , A$'? 367 appreciable ultraviolet absorption (anal. Found : mp (E 52,300) (anal. Found: C, 51.56; HI 4.32; C , 52.73; H, 7.43), which reacted with 1.05 N, 18.80), demonstrating the presence of two equivalents of sodium periodate and is formulated carbonyl functions; the infrared data shows that as VIII. This product readily underwent conthe remaining oxygen atoms are present as ether version to a ketolactone, AgE" 5.60, 5.83 p (posilinkages. The absence of ethylenic bonds in the tive iodoform test), characterized as its 2,4:-dinitrodimer was indicated by its infrared spectrum and phenylhydrazone, m.p. 177-179', A22 3.05, 5.62, 351 p (E 21,900) (awl. Found: by its failure to react with potassium permanganate 6.19, 6.29 p, solution, to give a color with tetranitromethane, C,48.42; H, 4.46; N,17.09),and assigned structure and to absorb hydrogen over palladium-char~oal.~ IX. This evidence is compatible only with the formuThe dimer reverted to the pyrone when warmed with dilute acid. It is assigned the cage structure lation of the dimer as 17; its ultraviolet spectrum I on the basis of these properties and the following is anomalous and the band a t 233 mp presumably has its origin in transannular interactions? evidence.
A:eN
(6) Cf. L. Malaprade, Bull. SOC. chim. Francs, [5], 1, 833 (1934); P. W. Clutterbuck and F. Reuter, J . Chem. Soc., 1467 (1935). (7) The reduction products previously noted' may be rationalized in terms of hydrogenation and hydrogenolysis of the carbonyl groups. (8) C f . M. Simonetta and S. Winstein, THISJ O ~ N A L 76, , 18 (1954), Footnote 19. (9) Public Health Service Research Fellow, 1958.
DEPARTMENT OF CHEMISTRY PETERYATES HARVARD UNIVERSITY MARGARETJEFBAIM J O R G E N W ~ ~ CAMBRIDGE, MASSACHUSETTS RECEIVED OCTOBER 2, 1958
p
o
n v
IV
IX
VI, Rt = Rz = Rg = OH VII, Rt = R3 = OCOC~HE.,R2 == OH VIII, R1 = COpH, Rz H, R3 OH
A NEW ALDEHYDE SYNTHESIS Sir : We have found that the Wittig olefin synthesis' can be extended to the synthesis of certain aldehydes by way of their enol ethers:
Reaction with perbenzoic acid gave a ketolactone, [( C~HE.)~PCHZOCH~] 'C15.76, 5.87 p, high intensity (CsH6)aP ClCHzOCHs dec.a ca. 280°, I end ultraviolet absorption (anal. Found: C, 63.82; C&Li H, 6.01), which is formulated as 11.6 Longer I 6(C&6)aP=CHOCH3 treatment with perbenzoic acid afforded two isoI1 meric dilactones, 111, de^.^ 280'. 5.75 p, end ultraviolet absorption (anal. Found: C, I I1 I HaO@ I -C=O +-C=CHOCHa W -CHCHO 59.96; H, 5.72), and IV, de^.^ 340-350°, A::a!' 5.75 p, end ultraviolet absorption (anal. Found: Triphenyl- (methoxymethyl)-phosphonium chloC, 60.07; H, 5.86). Hydrolysis of I11 gave iso- ride (I) (m.p. 191-193O; Calcd for CmHmClOP: dehydroacetic acid (V) and a product, m . ~ . C1, ~ 10.34. Found: C1, 10.24) from triphenylphosphine and chloromethyl methyl ether, was (1) See, for example, D. H. R. Barton apd G. Quinkert, Proc. Chem. Soc., 197 (1958); D. H. R. Barton and W. C. Taylor, J . Chem. finely powdered, suspended in anhydrous ether, SOL,2500 (1958); D. H. R. Barton, P. de Mayo and M. Shafiq, ibid., and stirred under a nitrogen atmosphere while one 140 (1958); E . E. van Tamelen, S. H. Levin, G. Brenner, J. Wolinsky equivalent of ethereal phenyl lithium was gradually and P. Aldrich, Tnxs JOURNAL, Soc., 80, 501 (1958); G. Biichi and added. The resulting deep red solution, presumI. M. Goldman, ibid., 79, 4741 (1957); G. Biichi and N. Yang, ibid., 79, 2318 (1957); R. C. Cookson, E. Crundwell and J. Hudec, Chemisably containing. methoxymethylenetriphenylphost r y and Industry, 1003 (1958); E. Zavarin, J . Org. Chem., 98, 47 phorane (11) in two-fold excess, reacted with 5a,(1958). 22P,25D-spirostan-3-one2 (tigogenone), yielding (2) E. PatunB; Guzs. chim. itat., 44, 151 (1914); M. Guia and 85% of 3-methoxymethylene-5cr,22~,25D-spiroM. Civera, ibid., 81, 875 (1951). (3) Sealed capillary. stane (111) (m.p. 178-181°, [aI2'D -65.8", Pmar. (4) Hydrogenation over platinum reduced the carbonyl gioups 1683 em.-'. Calcd. for C2sH~03: C, 78.68; HI to give a mixture of hydroxyethers, characterized ria their acetates 10.47. Found: C,78.90; HI 10.37). Brief treat80 Ci~H1a0dOHh(two isomers) and CI'HI~OZ(OH),and an ether,
+
Cid3mOa.
(S) The elemental analysis of this product confirms the formulation of 1 as a dimer rather than a trimer, in accord with the earlier molecular weight determinations.'
(1) For leading references, see G. Wittig, Angcw. Chemic, 68, 505 (1956). (2) R. W. Marker, T. Tsukamoto and D. L. Turner, THISJOURNAL, 6'1, 2525 (1940).
