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HAROLD H. ZEISS AND DWIGHT il. PEASE, JR.
Vol. 7s
the first 60 rnl. of effluent, in an amount of 103 mg. ( I l . Z ~ ~ ) , D-glucitol ( X I ) with Nitrosyl Chloride.-The deamination m.p. and mixed m.p. with an authentic sample prepared was carried out in a manner similar to the one described above. Chromatography of the product yielded 87 mg. of by the reaction of thionyl chloride in pyridine XTith D-isoXXI from 0.72 g. of XII; the yield was 9.59'0. mannide (I),*6 67". Reaction of 2,5-Diamino-2,5-dideoxy-l,4: 3,6-dianhydroCAMBRIDGE, MASSACHUSETTS
[CONTRIBUTION NO.
Chromate Esters. BY
1338 FROM
STERLING CHEMISTRY
LABORATORY, YALE
UNIVERSITY]
11. Reactions of Di-2-methylfenchyl Chromate1s2
HAROLD H. ZEISS3 AND DWIGHT A.
PEASE, JR.
RECEIVEDDECEMBER 7, 1955 The behavior of the chromate ester of 2-methylfenchol under varied solvolytic conditions has been examined, These results, together with those obtained from the chromic acid oxidation of 2methylfenchol itself and of a mixture of l-methylcamphene and 1-methyl-a-fenchene. are used t o delineate the path by which tertiary alcohols are oxidized and tertiary chromates react as oxidizing agents.
I n the first paper of this series4the formation and wise failed to undergo rearrangement under equivasolvolysis of an aliphatic tertiary chromate ester are lent circumstances. Then also, the action of demonstrated to occur with retention of configura- methoxide ion on I regenerated I1 without reartion a t the tertiary carbon atom. In the present rangement. paper we describe the chemical properties of a very LI AI H, stable bicyclic tertiary chromate ester in order to delineate as closely as possible the path by which tertiary alcohols are oxidized. As a corollary to these studies the function of tertiary chromate esters as oxidizing agents is adduced. The first chromate ester to be isolated by Wienhaus, di-2-methylfenchyl chromate (I) , was preI U pared by the usual methods5 and also by the use of chromyl chloride4from 2-methylfenchol (11). Since our preparation commenced with almost racemic CYfenchone, the chromate ester with which we worked ~~~~~ was a mixture of exo and endo i ~ o m e r s . However, the stereoisomeric composition of the ester is quite reproducible as are the results, kineticg and chemical,obtained with it. By analogy with the isoborneol-borneol system it may be anticipated that the exo (C-2 methyl) forms of the diester will rearrange more rapidly than the endo forms during In H reaction. However, both types of esters should deThe diester I was solvolyzed in methanol a t 25, compose to the same products, albeit in different ra46 and 65", and, although the products were the tios, and thus produce no difficulties in the intersame regardless of the temperature, a t 25" less than pretation of the results. Reduction of this red, crystalline ester with lith- 20% of I had reacted after 4 days. At 46" reaction ium aluminum hydride provided structurally pure was substantially complete in this period of time, 11, spectroscopically similar in the infrared region and a t 65" methanolysis time was less than 24 to that purified oia the half phthalate ester and sub- hours. The products from a sealed tube reaction sequent reduction with the same reagent. This a t 65" were the parent alcohol 11, a mixture of 1reaction cycle ensures the absence of rearrangement methylcamphene (V) and 1methyl-a-fenchene of the fenchyl structure to that of bornyl and es- (VI), an apparenr mixture of the methyl ethers of tablishes the fact that it resides intact in the I1 and IV, formaldehyde and an insoluble organochromate ester. Further, it confirms the stereo- chromium compound analyzing for trimethoxychemical evidence for the observed maintenance of chromium. The presence of methyl ether is indiasymmetric identity in optically active 2,4-di- cated by comparison of the 8.5-9.5 p infrared region methyl-4-hexanol throughout a similar cycle.4 The of the product with that of an authentic sample of structural isomer of 11, 2-methylborneol (IV), like- the methyl ether of 11; and i t is inferred that a mixture of the ethers of 11 and 1V is present on the (1) This work was supported in large part b y Contract No. DA-19basis of the reasonable mechanism proposed below. 059-ORD-849 between t h e Office of Ordnance Research, U. S. Army, The main product was 2-methylfenchol (61%) unand Yale University. accompanied by IV. I n the incomplete run a t 25" (2) Taken from t h e Ph.D. dissertation of D. A. Pease, Jr., Yale University, 1954, and presented in p a r t a t Los Angeles, Calif., March the recovered ester I contained none of 111. It is 18, 1953, Abstr., IZ3rd Meeting. Am. Chem. SOC.,p. 30M. concluded, therefore, that the decomposition of I is (3) Monsanto Chemical Co., Dayton 7, Ohio. irreversible with respect to any process involving (4) H. H. Zeiss and C. N. Matthews, THISJOURNAL, 7 8 , 1694 (1956). the reformation of I subsequent to or during the (5) H. Wienhaus, Ber., 41,322 (1914).
REACTIONS OF DI-2-METHYLFENCHYL CHROMATE
July 5 , 1956
rearrangement to the bornyl structure (VI and the methyl ether of IV) . Inherent in this conclusion is the assumption of the separation of tertiary carbon-oxygen bonds with consequent (1) elimination to a mixture of olefins or (2) methanolysis t o a mixture of the methyl ethers of I1 and IV.
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of V and VI, an apparent mixture of the methyl ethers of I1 and IV and the insoluble organochromium compound. However, the yield of IV was only 41% as compared to 61% of I1 above, and the amount of V and VI rose from ISYO in the methanolysis of I to 24y0in the present case. This indicates, perhaps, that the decomposition of I11 by alkyl-oxygen fission is a more favorable reaction path than of I. Wave numbers. 14001200
P 5000 3000
1000 900
800
+ P + HCHO O -
