the rapid passage technique in order to observe the BI1 resonance a t +20 p.p.m. in the same medium. The study of photochromism in mesomeric phosphonium salts and other organophosphorus compounds is continuing.
chromatographic analysis indicated a ratio of insertion into primary vs. secondary carbonhydrogen bonds of 0.05 for both photolysis and pyrolysis. The remarkable reactivity differences of chlorocarbene derived from the diazocompound and of CLIFFORD S.ATTH THEWS the formally identical intermediate in a-elimination MONSASTO RESEARCH CORPORATION JOHS S. DRISCOLL from methylene chloride4 is noteworthy. The BOSTOSLABORATORIES J O H N E HARRIS failure of the latter intermediate to insert into 49, MASSACIWSETTS KORERTJ WIVEMAN carbon-hydrogen bonds and its relatively high EVERETT RECEIVED OCTOBER 8, 196:' steric discrimination in additions to olefins6 (e.g. ratio of the two I -chloro-cis-2,3-dimethylcycloTHE PREPARATION, PYROLYSIS AND PHOTOLYSIS propanes resulting from the addition to cis-2butene is 5.5)6suggests that in the a-eliminations OF CHLORODIAZOMETHANE1 a truly free carbene might be bypassed.' Sir : ( 6 ) G. L. Closs and G. >I. Schwartz, ibid., 82, 5729 (1960). Halogen derivatives of diazomethane are of (7) Cf. the similar observations for diphenylcarbene; G. I,. Closs interest as potential precursors of divalent carbon Angew. Chem., 74, 431 (1962). intermediates. Particularly, comparison of re- and(8)L.A.E.P.Closs, Sloan Foundation Fellow, 1962-190.1. activities of halomethylenes derived from such diDEPARTYEST OF CHEMISTRY G. L. CLOSS* azocompounds with those of the formally identical THEUNIVERSITY OF CHICAGO carbenes generated by a-eliminations promises to CHICAGO 37, ILLINOIS J. J. COYLE give new insights into some problems of carbene RECEIVED SEPTEMBER 21, 1962 chemistry.2 We wish to report the preparation of solutions of chlorodiazomethane and some of their ON THE MECHANISM OF ERGOT ALKALOID physical and chemical properties. BIOGENESIS' Reactions of t-butyl hypochlorite with dilute Sir : solutions of diazomethane in ether or hydrocarbons Although the biogenetic origin of the C-8 suba t -100' give solutions of a red compound which we believe to be chlorodiazomethane on the basis of stituted N-methylergoline skeleton of the ergot the following observations : The electronic absorp- dlkaloids has been established as arising from tion spectrum in pentane exhibits a bathochromic tryptophan,2 mevalonate2 and the S-methyl of shift relative to diazomethane with three maxima methionine, the mechanism of the biosynthesis of about equal intensities a t 485, 518 and ,745 mp is still unknown. The association of mevalonic acid (I) with tryptoi E about 15),3 respectively. The infrared spectrum shows a strong band a t 2066 ern.-' attributed phan (111) involves the bond formation of C-5 of to the stretching vibration of a diazo group (z'P. mevalonate (I) with the C-4 and a-carbon of tryp2097 cni.-l for diazomethane). The solutions tophan (111), and the C-3' of mevalonate (I) with slowly decolorize with loss of nitrogen a t tempera- the a-amino group of tryptophan (111),respectively tures above -40'. Reactions with carboxylic In order to obtain information on the mechanism acids lead to rapid nitrogen evolution and de- of the formation of the new C-C linkages and of the colorization. Chloromethyl acetate and chloro- biosynthetic route by which the different substituents appear a t C-8 of the ergot alkaloids, the methyl propionate have been prepared in this way. Confirming evidence for the structure of the chlo- changes in the oxidation state a t C-5 and C-2 of rination product was obtained from the pyrolytic mevalonate were examined during its conversion i- 20') and photolytic (-80') decompositions of into ergot alkaloids. During the over-all biosynthetic reaction the these solutions. Using olefins as solvents, satisfactory (30-40yc) yields of chlorocyclopropanes T,Cl4 ratio of DL-mevalonic acid-2-C14-5-T comwere isolated. Thus, trans-2-butene reacted stereo- pared to the same ratio of the ergot alkaloid (festuspecifically to give 1-chloro-fr~ns-2.~-dimethylcpclo-clavine and pyroclavine) has been changed to a propane while ris-2-butcnc gave the two epimeric degree which indicates the net loss of 1 atom of hy1 - chloro - c i s - 2.3 - dimethplcyclo~iropallesin cqu?l drogen. The T,Cl4 ratio of rx-mevalonic acidcluantities. Similarly. with cyclohexene both T- 2-C14-2-T did n o t change during its conversion chloronorcareries were formed in a 1 : 1 ratio. ' into agroclavine, indicating that there is no change Froin reactions in n-pentane the three possible in the oxidation level a t C-2 of mevalonate during carbon--hydrogen insertion products, I -chloro- the biosynthesis (Table I). The loss of one atom of hydrogen from DLhexane. 1-chloro-2-niethylpentane and l-chloro-2ethylbutane, have been identified.j Vapor phase mevalonic acid-2-C14-5-T may be associated with the oxidation of the primary alcoholic group of (1) Supported by a grant from t h e Petroleum Research Fund, admevalonate (I) into an aldehyde group before its ministered by t h e American Chemical Society. bond formation with tryptophan. Another pos(2) For a recent review see: W. Rirmse, Angcw. Clienz., 73, 161 sibility which may exist is that the first bond for(1961). ( 3 ) Since a satisfactury method for assaying t h e chlorodiazomethane mation occurs without any change in the oxidation ~
wlutionb has not yet been found, the c value is based on a n estimated yield of ,505; and undoubtedly will he subject t o revision. ( 4 ) Ci.G . I.. Closb and I.. 12. Closs, .I. A m C h ~ m .S o ( . , 82, 3 7 2 3 IlOIiO).
12) These compounds were isolated by v.p.c. and their ini'rarrd s l x c Ira wi'rr comi>art.,l w i t h t h u w
