A protocol for applying substrates with chiral methyl groups to determine the stereochemistry of enzymic hydroxylation of methyl groups is discussed. Efficient methods are described for the synthesis of (R)-[1-2H,1-3H]- and [1,1,10,10-2H4]-decane from decanal and diethyl sebacate, respectively. Decanal was converted via the 2-anion of 2-nonyl-1,3-dithian to [1-3H]decanal which was reduced to (S)-[1-3H]decan-1-ol by NADH–liver alcohol dehydrogenase. Tosylation of the decanol, followed by reduction with Li[Al2H4] gave (R)-[1-2H,1-3H]-decane (specific activity 0.095 Ci mol–1). Diethyl sebacate was reduced with Li[Al2H4] to [1,1,10,10-2H4] decane-1,10-diol. Conversion of the diol to its ditosylate and reduction with Li[AlH4] gave [1,1,10,10-2H4]-decane. Although these procedures are essentially adaptations of literature methods, several significant improvements are described. The protonation (deuteriation, tritiation) of the 2-anion of 2-nonyl-1,3-dithian shows an inverse isotope effect, the magnitude of which has been explored for 2-anions of several 2-alkyl- and 2-aryl-1,3-dithianes (see Table).
Abstract Derivatives of 5H-cyclopenta[2,1-b:3,4-b']-dipyridin-5-one including representatives of the new heterocyclic diquaternary system 4H-7a,9a-diazoniacyclopenta[def ]phenanthrene have been synthesised and the herbicidal and redox properties of the salts studied. The mass spectrum of 5-hydroxy-5-methyl-5H-cyclopenta-[2,1-b: 3,4-b'Jdipyridine is also reported.
1,5-Naphthyridine and 1,8-naphthyridine react with dimethyl sulphate and with ethylene dibromide, respectively, to form 1,5-dimethyl-1,5-naphthyridinedi-ium dimethosulphate and 5,6-dihydroimidazo[1,2,3-ij][1,8]naphthyridinedi-ium dibromide. The salts readily form pseudo-bases. The salt from 1,5-naphthyridine is reduced by a one-electron transfer to give a relatively stable green radical cation.
Abstract 1,5‐Naphthyridin (I) reagiert mit Dimethylsulfat im Überschuß unter Bildung des Naphthyridindiumdirnethosulfats (II), das in wäßriger Lösung mit′ seiner Pseudobase im Gleichgewicht steht.
The principal methods for the generation of arynes,
and the Diels–Alder reactions of steroidal dienes are
briefly reviewed.
Tetrafluorobenzyne (generated from pentafluorophenyl-lithium and pentafluorophenyl magnesium chloride) reacts
with simple models for steroidal diene systems to give
mainly 1,4-addition products.
Benzyne (generated from o-bromofluorobenzene and
anthranilic acid), tetrachlorobenzyne (from tetrachloroanthranilic
acid) and tetrafluorobenzyne react with
steroidal-5,7-dienes to give products of the ene-reaction.
In addition, tetrafluorobenzyne forms a 5,8-adduct with a
5,7-diene and with a 5,7,9(11)-triene.
Cholesta-2,4-diene gives 1,4-adducts with benzyne and
tetrafluorobenzyne which undergo retro-Diels–Alder reactions
on pyrolysis. Steroidal-1(10),9(11)-dienes also give 1,11-adducts
with benzyne and tetrachlorobenzyne.
The adducts of tetrafluorobenzyne with models for the oestrogen
steroids, and with oestradiol dimethyl ether are reported. An
unsuccessful attempt to synthesise an adduct from a steroidal
styrene is described.
Finally the photoisomerisation of 5,6,7,8-tetrafluoro-1,4-dihydro-1,4-ethanonaphthalene is reported and a mechanism proposed.
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