Communications
J . Org. Chem., Vol. 42, No. 17,1977 2951
92%) ['H NMR (CC14) 6 2.3-2.0 (m, 2 H),7.6-5.5 (m, 2 H)]. VPC analysis showed an 8:92ratio of 4bbb.8 Thus, it is now possible to convert monosubstituted alkenes to either 2-phenylselenoalkenes 4 or 1-phenylselenoalkenes 5 regioselectively. We are currently developing a variety of synthetic transformations for these substances and will report on them in due course.
to have been explored. In fact, such base-catalyzed chemistry of any pteridines seems limited to the conversion of the Nsubstituted 3,5,74rimethylxanthopterin(4) to methyl ester 5 using dimethyl oxalate in the presence of potassium methoxide,2 and to the reaction of N8-lithio salts of various 2,4diamino-7,8-dihydropteridines with alkyl halides to afford Ns-alkyl derivatives 6.3
References and Notes
I:
( 1) Organoselenium Chemistry. 1. This research was supported in pari by a grant
from the Petroleum Research Fund, administeredby the American Chemical Society. (2) (a) D. L. Klayman and W. H. H. Gunther, Ed., "Organic Selenium Compounds: Their Chemistry and Biology", Wiley-lnterscience, New York, N.Y., 1973; (b) K. B. Sharpless, R. F. Law,D. W. Patrick, S. P. Singer, and M.W. Young, Chem. Scr., 8A, 9 (1975), and references cited therein; (c) H. J. Reich and S. K. Shah, J. Am. Chem. Soc., 99, 263 (1977), and references cited therein. (3) We have successfully utilized vinyl phenylselenides as synthons for the construction of new carbon to carbon bonds. This work will be reported soon. (4) (a) Stable seleniranium ions have recently been prepared by the reaction of ArSePFe with alkenes: G. H. Schmid and D. G. Garrett, Tetrahedron Lett., 3991 (1975).(b) PhWIreacts with propene in CHzCI?to give a 1:l mixture of i and ii (R = CH3, X = CI), and in HOAc to give li (R = CHI, X = CI) exclusively: E. G. Kataev, T. G. Mannafov, E. A. Berdnikov, and 0. A. Komarovskaya, Zh. Org. Khim., 9, 1983 (1973); D. G. Garrett and G. H. Schmld, J. Org. Chem.. 42, 1776 (1977). (c) PhSeOAc reacts with ldodecene to give a 1:l mixture of I and il (R = rbCt0H2,, X = OAc): K. B. Sharpless and R. F.Lauer, J. Org. Chem., 39,429 (1974). (d) PhSeOCOCF3 gives mixtures of adducts with 1-methylcyclohexene and 1-hexene: H. J. Reich, J. Org. Chem., 39,428 (1974); S. Raucher, Unpublished results. (e) For studles of the regloselectivity of PhSCl see W. H. Mueller and P. E. Butler, J. Am. Chem. Soc., 90, 2075 (1968); D. G. Garrett and G. H. Schmid, J. Org. Chem., 42, 1776 (1977) RCH(SePh)CH2X RCH(X)CHzSePh i ii (5) This isomerization presumably involves the reversible formation of the seleniranium ion and the rate is dependent on the leaving group, X. For example, we have observed that for R = rbC4H9, i isomerizes to ii in 85 % in all instances. (c) VPC analysis was carried out on a Varian 920 using a 5 ft X y4 in. 1.5% OV 101 on 1001120 Chromosorb G column at 60 mL Helmin. In all cases, the retentiontlme of 4 was less than that of 5. Ratios were determined by triangulation of peaks. (d) A sample of 5b was prepared by the reaction of Ph3P==CHSePhwith pentanal: N. Petragnani, R. Rodrigues, and J. V. Comasseto, J. Organornet. Chem., 114, 281 (1976); a sample of 4a was prepared by an alternate procedure which will be detailed shortly: S. Raucher and G. Koolpe, unpublished results. (9) The rate of disappearanceof the dark brown color (THF, -78 'C) is
