Bacterial Carotenoids. XIX. The Carotenoids of Mycobacterium phlei Strain Vera. 1. The Structures of the Minor Carotenoids.

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Abstract
Under the cultural conditions specified, M. phlei strain Vera, produced as minor carotenoids the nonocyclic compounds gamma-carotene (I). 1[image]2[image]-dihydro-1[image]-hydroxy-gamma-carotene (II), 4-keto-gamma-carotene (III) and 1[image]2[image]-dihydro-1[image]-hydroxy-4-keto-gamma-carotene (VI). The structures of the three latter carotenoids were established by dehydration with phosphorus oxy chloride of II to I, and VI to III, by hydride reduction of VI to 1[image],2[image] -dihydro-4,1[image]-dihydroxy-gamma-carotene (VH) and of into 4-hydroxy-gamma-carotene (IV) and further allylic dehydration of IV to retro-dehydro-gamma-carotene (V). Finally I, II, III, and VI were directly compared with the corresponding totally synthetic carotenoids, prepared by others; as were IV, V, and VII here prepared from the natural and totally synthetic samples. This is the first finding of II, III, and VI in Nature; only IK was obtained in the crystalline state. The structure of the major carotenoid, here called phlei-xanthophyll, was different from that of myxoxanthophyll, and will be discussed in a later paper.