摘要:
C hem ical Corn m u n i cations NUMBER 16/1965 25 AUGUST 1 -Adamantyl-lithium By PETER T. LANSBURY and JACK D. SIIILEK (Department of Chemistty, State University of N e w York at Bufflo, Buflalo, New York 14214, U . S . A . ) BRIDGEHEAD organometallic dcrivatives of adaman- tane have not yet been reportcd, in spite of several unsuccessful attempts to prepare them.1,2 In this communication, we report the first preparation of l-adamantyl-lithium (I) and also some observations on its tendency to give coupling products during formation, a consequence of the remarkable stability of the l-adamantyl free-radi~al.~ Using the metal-halogen exchange reaction4 p5 of equimolar amounts of t-butyl-lithium and 1- iodoadamantane at - 70" in ether-petroleum or tetrahydrofuran-petroleum, followed by quenching with ben~aldehyde,~ no adamantylphenylcarbinol (11) was obtained.Instead appreciable quantities of l,l'-bisadamantyl,sm.p. 288-290", wereisolated. Only bv using a 2 : 1 mole ratio of t-butyl-lithium to l-iodoadaniantane were we able to obtain 60-8076 yields of t-butylphenylcarbinol (111) and (11) (approximately equal amounts) when ether- petrc;lcum was solvent. Replacement of ether by tetrahydrofuran lowered the yield of (111) and again produced 1, 1'-bisadamantyl in high yield, with the exclusion of (II).* Phenyl isocyanate was also used as an electrophile for the exchange mixture, providing inter d i n 33% of l-adamantane- carboxanilide, m.p. 196.5-197.5", readily separated from pivalanilide by preparative V.P.C. The above results give little information on the relative stabilities of t-butyl-lithium 7Jewx.s (I) ; however none of the latter (or 1,l'-bisadamantyl) is formed from l-bicyclo [2,Z,2]octyl-lithium4 and l-iodo- adamantane.It is noteworthy that the major dinieric hydro- carbon detected in the above exchange reactions was 1, 1'-bisadamantyl. This observation is con- sistent with Applequist's findings on the extraord- inary stability of l-adamantyl radical^,^ compared with t-butyl and bicyclo-octyl radicals. Thus, previous unsucccssful attempts to prepare 1- adaniantyl organomctallic reagents can be rational- ized in terms of tht: electron-donating and -acceptor abilities of l-adamantyl-lithium and iodide, re- spectively, both features being responsible for facile coupling even a t -70". In contrast, t-butyl-lithium and t-butyl iodide under the above exchange conditions gave 600/, of (111) and ca. 10% of 2,2,3,3-tetramethylbutane. (Received, July 23rd, 1965; Corn. 463.) P. von R. Schleyer, personal communication. F. N. Stepanov and V. F. Baklan, J . Gen. Chem. U.S.S.R., 1964, 34, 580. D. E. Applequist and L. Kaplan, J . Amer. Chewz. Soc., 1965, 87, 2194. P. T. Lansbury and J. D. Sidler, Tetrahedron Letters, 1965, 691. D. E. Applequist and D. R. O'Brien, J . Amer. Chem. Soc., 1963, 85, 743. cz H. Reinhardt, J . Org. Chem., 1962, 27, 3258. ' P. T. Lansbury and V. A. Pattison, J . Org. Chem., 1962, 27, 1933. * The utility of tetrahydrofuran as a solvent for electron transfer reactions of organolithium reagents has been discussed by R. Waack and M. A. Doran, J . Orgnnometallic Chem., 1965, 3, 92.
ISSN:0009-241X
DOI:10.1039/C19650000373
出版商:RSC
年代:1965
数据来源: RSC