South Parks Road, Oxford OX1 3QYStructural investigation of the products obtained by microbiological hydroxylation of substrates in the androstane, pregnane, and mstrane series has involved examining the l H n.m.r. spectra of 344 steroids, 243 of them being new compounds. Mild oxidation of the products gives polyketones in which the positions of the oxo-groups are characterised by the chemical and solvent shifts of the 18-H and 19-H signals. This information is supplemented by the chemical shifts of the products' 18-H and 19-H signals, and by the positions and form of their )CH-OH resonances : the latter are especially useful in establishing the configurations of the hydroxy-groups.FOR the past five years we have been studying the hydroxylation of mono-and di-oxygenated steroids with a range of micro-0rganisrns.l The intention was to vary the positions of the oxygen substituents around the steroid nucleus in a systematic manner: it was -gate, ibid., 1969, 463. hoped that the use of relatively simple substrates would facilitate interpret at ion of the microbiological behaviour. A considerable body of results has accrued from examining monoketones, keto-alcohols, and diketones derived from handrostane, 5a-pregnane, and 5a-cestrane ; a series of papers describing the work will be submitted shortly to this Journal. The preparation of substrates and related chemical studies are being recorded in a separate series2
The synthesis of a series of diphenylpoly-ynes Ph*[CiC];Ph is described, those with n = 3, 4, 6, and 8 having been isolated and crystallised. Their ultra-violet and infra-red spectra are described and discussed, and compared with those of the corresponding polyenes.THE diphenylpolyenes (11) are much more stable than the purely aliphatic polyenes.Consequently, having prepared a number of aliphatic conjugated polyacetylenes (Cook, Jones, and Whiting, J., 1952, 2883) which on the whole proved to be rather unstable, we turned to the synthesis of the presumably more stable diphenylpoly-ynes (I). Such a project appeared additionally attractive since it offered the possibility of comparisons with the well-known diphenylpolyenes, synthesised and studied by Kuhn and his collaborators (for summary see J., 1938, 605).Four new members of the series (I), where n = 3, 4, 6, and 8, have been obtained, and the general laws defining their spectrographic properties elucidated. After the completion of most of this work, independent syntheses of (I; n = 3 and 4) (Nakagawa et aZ., Chem.
Polyacetylenic hydrocarbons with t-butyl end-groups and having eightTheir physical and ten conjugated acetylenic linkages have been prepared. properties are discussed. PARTS XXXIX and XLI described the preparation of polyacetylenic compounds with methyl and phenyl end-groups. For the former, the longest chain obtainable had six acetylenic linkages; and for the latter, eight. I n each case the last obtainable member of the series was extremely difficult to handle because of low solubility and instability. Independently, Bohlmann prepared a similar series of polyacetylenes having t-butyl groups at both ends. These hydrocarbons were obtained up to n = 7, and even this member of the series appeared, from the published description, to be soluble in most solvents and reasonably stable. These differences were plausibly explained as due to the ability of the bulky and cylindrically-symmetrical end-groups to keep the rod-like polyacetylenic chains well outside bonding distance. (At the same time, the possibility of attack, e.g., by free radicals, on any hydrogen atoms on a carbon atom at the end of the chain would obviously be eliminated.) The same principle was later applied, with outstandingly successful results, to the preparation of stable aliphatic c~mulenes.~ When electronic absorption spectra became accurately known for longer 4 (8-10) as well as shorter (3-7) polyenes with simple end-groups, it became desirable to extend similarly the range of known aliphatic polyacetylenes; the use of t-butyl end-groups was obviously necessary. It seemed that progress might be made in this direction by the use of penta-1,4-diyn-3-01, which became readily accessible only recently.6 In principle, it was necessary merely to modify a reaction scheme already used by Bohlmann:
The factors which determine the specific positions at which steroids are hydroxylated by micro-organisms are being investigated, using mono-ketones or keto-alcohols of the androstane series as substrates and infra-red and n.m.r. spectroscopy to determine the structures of the products. Whereas the major product of the hydroxylation of 5o-androstan-3-one by cultures of Calonectria decora is 123,l5x-dihydroxy-5eL-androstan-3-one, by contrast, with the 17-ketone as substrate, I I,6oc-dihydroxylation occurs. The hydroxyl groups The regio-specific reactions of organic compounds are usually associated with the presence of functional groups. Substitution is facilitated by bond polarization, i.e. the presence of a good leaving group or of adjacent activat.ion. Substitution at remote sites can only be achieved by transmitting these effects by appropriate means. The organic chemist has become very ingenious at this, constructing scaffolding enabling him to activate remote positions.In recent years, however, we have seen developments in what is now
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