4120
C. D. ROBESON, W. P. BLUM,J. h l . DIETERLE,J. D. CAWLEY AND J. G. UAXTER
[CONTRIBUTIOLK F R O M T H E
RESEARCH LABORATORIES O F DISTILLATIOX PRODUCTS KODAKC O M P A N Y ]
T'ol. T i
I N D U S T R I E S , DIVISIOS O F EASTMAN
Chemistry of Vitamin A.
XXV. Geometrical Isomers of Vitamin A Aldehyde and an Isomer of its a-Ionone Analog1 BY C. D. KOBESOX,W. P.BLUM,J. M. DIETERLE,J. D. CIWLEY .WD J. (2.H.IXTBK RECEIVED AUGUST24, l9,X
The preparation of four, synthetic geometrical isomers of vitamin A aldehyde (identified as all-trnns, h i s , 2,(i-di-cis, 6;c-is) is described. Their ultraviolet absorption spectra, infrared spectra and other physical and chemical properties arc given. The configuration of a fifth isomer of vitamin A aldehyde, neoretinene-b, was also studied. A 2,4-di-cis qtructure was preferred for i t over a possible 2-trans, 4-cis configuration. An all-trans "a-vitamin A aldehyde" was synthesized from a-ionone. Its properties were different from those of the 6-cis and 2,6-di-cis isomers which excluded the possibility that t h e latter two compounds might be geometrical isomers of a-vitamin A aldehyde.
I n the previous paper in this series2 a synthesis of vitamin A is described by which four crystalline geometrical isomers were prepared. These were identified as the all-trans, 2-cis, 6 4 s and 2,B-di-cis forms, according t o the following numbering system CHI CHI
CH3 \/ ~~-;H=cH-C=CH-CH=CH-A=CH-CH~OH 8 7 6 5 4 3 ? 1
*CH3
Similar reactions were employed to synthesize an "a-vitamin A" in which the ring double bond was shifted out of conjugation with the side chain, as in a-ionone. After oxidation with manganese dioxide,3 the corresponding crystalline vitamin aldehydes were prepared, together with a number of deriva-
tives. Some of the properties of these compounds are given in Table I. These properties in conjunction with published properties on three isomers, assigned the all-trans, %cis, 6 4 s configurations (Table I, footnotes) supported the structural assignments made in reference 2 and indicated that no change in configuration had occurred during oxidation. The %,6-di-cisisomer has not been described previously and its assigned structure was based on ' t h a t assigned the parent vitamin A as well as on confirmatory evidence obtained from infrared data presented later in this paper. The a-vitamin -4. aldehyde isomer we prepared has also not been described before. It was assigned an all-fmns configuration, partly because of its failure to isomerize with acid reagents to an isomer absorbing a t a longer wave length and because of its infrared spectrum.
TABLE I PROPERTIES OF ISOMERS A N D DERIVATIVES OF VITAMIN A ALDEHYDE Isomer or derivative
mp., OC.
Absorption" Xmax, nw
E17
1 Crn
SbCla reaction product Xmax, mp I
All-trans" 57, 6 j h 381 1530 43,400 6(jl X 7 0 Methyl riicotiiiiuin p-tolueriesulfonate 1iytlr:izone 192.-5 395 892 52, ,500 -2,4-dinitrophenylhydrazone( D S P H ) 211 263,350,418 373,411, 111.5 -, -, c51,700(C€IC13) -sulfanilamide Schiff base l(Z 403 1335 58,500 -paminoazobenzene Schiff basc 138.5 122 1340 62,20i) -,. , I 237, 37.5 Seo- (a-cis, neoretinene-ald :i:3B, 1250 --, 35,600 ijG4 :$-$!)I 1 2,6-di-cis (isoretinene-b) 49, 85" 368 1140 32,400 664 3490 -DNPH derivative 209 425 1020 47,300 ICHCI?) &cis ("cis-" vitamin A aldehyde, isoretinene-a)' 64 373 1270 36,100 661 3470 -DNPH derivative 189 438 10TO 49,7(10 192 294, : x 2 , 373 886, 211(1,2120 -, ---, 72,:30(! -semicarbazone 04.5 254,376 595, 8.57 Seoretineiie-b (2,1-di-cis-vitainiii rl altlchytlc)' 16,950, 24,4i)O 664 3498 a-1-itarnin A aldehyde (all-trans) 85.5 250,368 284, 1720 -, 48,801) ,561 4420 -seniicarbazone 195 34:3, 358, 378 1630, 2580, 2350 -, 88,Oi)O,- D S P H derivative 18.5 255, 350, 420 513, 391, 1100 -, -, 51,100 (CI-IC13) Iii absolutc ethanol unless otherwise specifietl. " Diinorphic forni
