Asymmetric induction in a new domino reaction of [3,3]-sigmatropic rearrangement of allylic thiocyanates and intramolecular heterocyclisation (original) (raw)
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The synthesis of 8-thiabicyclo[3.2.1]octanes, as structural mimics of the tropane alkaloids, was undertaken and, in particular, the feasibility of functional group modification at certain ring positions was investigated. In Chapter 1, functional group changes were effected at C(6) and C(7) of 6,7-dichloro-8-thiabicyclo[3.2.1]octane (107) which reacted with weaker nucleophiles, such as water, alcohols, catechol, 1,2-diaminobenzene, ethanoic acid and ethanoate ion, forming substitution products with stereochemical retention, replacements generally being faster in the presence of zinc metal. Substitution did not proceed at all with the stronger nucleophiles AlH4 , OR, I, or Et3N. In presence of zinc, (107) underwent elimination with CN-, 1,2-diaminoethane and glycine for- ming (114). With phenol/Zn, both substitution and elimiantion took place to yield (134). (107) underwent a novel stereospe- cific oxidation-dichlorination with NaOH forming (126). Similar reactivity was observed for t...
The Journal of Organic Chemistry, 2006
The reaction of mono-and dilithiated ethyl thioglycolate with 1,2-diimidoyl-1,2-dichloroethanes, azaanalogues of oxalyl chloride, afforded (depending on the reaction conditions) 3-imino-1,2-dithia-3Hcyclopent-4-enes, 3-amino-2-thioxo-2,5H-pyrrol-5-ones, and 2,3-diamino-4-thioxo-4H-thiopyrans. The reaction of the dianion of ethyl hippurate with 1,2-diimidoyl-1,2-dichloroethanes afforded 6-imino-6H-1,3-oxazines.
European Journal of Medicinal Chemistry, 1997
A compound endowed with coanthracvchnic activity should potentiate the antitumor activity of anthracyclines while counteracting their cardlodepressant effect. We now report the synthesis and configuration of a series of substituted 3-(5-imidazo[2,1-b]thiazolylmethyleneF2-indohnones which were tested for both cardlotonic and cytotoxlc activity. Several compounds were potent cytotoxic agents and two of them (in particular 3-[6-(2,5-dimethoxyphenyl)-5-imidazo[2,1-b]thlazolylmethylene]-2-indolinone), which showed even cardlotomc activity, are potential coanthracychnlc agents.
Direct Synthetic Approach to N-Substituted 1-Amino-2,3-dihydro-1H-imidazole-2-thiones
HETEROCYCLES, 1997
In an efficient one-pot procedure, the title compounds (8) were obtained by the reaction of a-halo ketones (1) with potassium thiocyanate and monosubstituted hydrazines (3). The reaction is considered to proceed via the formation of azo-alkenes (5) and thiocyanic acid. These intermediates, in turn, undergo a [3+2] cycloaddition reaction; the resultant azomethine imine cycloadducts (6) are transformed into the final products (8). The structure of compounds (8) has been confirmed by utilization of various NMR techniques.