Ergot alkaloids, hydrogenate

Synonyms. Co-dergocrine Methanesulphonate DEA DHAE Dihydroergotoxine Mesylate Dihydrogenated Ergot Alkaloids Hydrogenated Ergot Alkaloids. 

P-Blockers yield yellow to pink-colored chromatogram zones on a colorless ba ground, which, like the zones of the ergot alkaloids and hydrogenated ergot alkalo can usually be exdted to blue fluorescence on irradiation with long-wavelength UV li (A, = 365 nm) [1, 3]. 

Some of these natural products—and drugs made from them—are known collectively as the ergot alkaloids, and have found use in medicine. Ergonovine, for example, is a selective stimulant for contraction of uterine muscle and is used in conjunction with labor and delivery. A mixture of hydrogenated ergot alkaloids—reduced at the 9,10-position—has found... 

The principal interest in the acetylation of this ring system resides in the preparation of substituted protected a-hydroxy acyl derivatives 134 which on deprotection spontaneously cyclize to the fused oxazolo systems 135 which are present in certain ergot alkaloids and are of some pharmacological interest. Frequently the oily benzyloxyacyl derivatives are not purified but are immediately hydrogenated to give the solid oxazolo compounds. 

Finally if the steps which lie between chanoclavine-I and proton removal are reversible and if proton abstraction is rate-limiting, the tritium enrichment of unreacted chanoclavine-I, which was observed in the above experiments, is also explained. (Loss of tritium is slower than loss of hydrogen as the result of a primary isotope effect.) So we now have a most satisfying rationale for the steps involved in the formation of the tetracyclic ergot alkaloids from chanoclavine-I. 

The cyclization 334 - 335 in ergot alkaloid biosynthesis has been shown to involve loss of the 3-pro-S hydrogen of tryptophan in the process, casting light on the stereochemistry of the ring closure step (336). 

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