Novel rearrangements of <i>N</i>‐arylpyrrolyl sulphides

Cheeseman, G. W. H.; Hawi, Amale

doi:10.1002/jhet.5570200318

Cited by 12 publications

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“…Each of these highly reactive reaction centers combines the chemistry of pyrroles with the equally rich chemistry of nitriles, carbanions, and organosulfur compounds, including that of the pyrrole series . Nevertheless, to the best of our knowledge, so far only two representatives of 2‐(cyanomethylsulfanyl)‐1 H ‐pyrroles have been synthesized [by selective reduction of 1‐(2‐nitro‐ or 2‐cyanophenyl)‐2‐thiocyanato‐1 H ‐pyrrole with sodium borohydride followed by treating of the resulting thiol (the latter was not isolated) with chloroacetonitrile] (Scheme ) and utilized as useful precursors of (2‐nitrophenyl)(1 H ‐pyrrol‐2‐ylsulfanyl)acetonitrile, pyrrolo[1,2‐ a ][3.1.6]benzothiadiazocine‐7‐oxide, and 6‐aminopyrrolo[1,2‐ a ][3,1]benzothiazepine‐5‐carbonitrile (Scheme ).…”

Section: Introductionmentioning

confidence: 99%

2‐Amino‐5‐(cyanomethylsulfanyl)‐1H‐pyrroles from Propargylamines, Isothiocyanates, and Bromoacetonitrile by One‐Pot Synthetic Protocol

et al. 2020

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Tertiary propargylamines (such as N,N-dialkylpropargylamines, N-propargylpyrrolidine, -piperidine, and -morpholine), isothiocyanates, and bromoacetonitrile have been shown to be readily available building blocks for the highly selective one-pot construction of rare-functionalized pyrroles, namely so far inaccessible 1-substituted 2-amino-5-(cyanomethylsulfanyl)-1Hpyrroles, in up to 92 % yield. This highly efficient and operationally simple approach includes the initial formation of lithium but-2-ynimidothioate (adduct of monolithiated propargylamine and isothiocyanate), its transformation into potassium buta-2,3dienimidothioate under the action of the t-BuOK/DMSO system (through acetylene-allene isomerization and the exchange by cations), intramolecular cyclization into potassium thienylamide (at � 15°C), followed by its re-cyclization into potassium pyrrolylsulfide at a higher temperature (45-60°C), and the final S-alkylation of the latter with bromoacetonitrile. The total reaction time is 45-60 min.[a] Dr. Scheme 4. Plausible mechanism of pyrrole ring construction from propargylamines 1 and isothiocyanates.Scheme 5. Reaction products obtained from lithiated propargylamine 1 b and 2-(vinyloxy)ethyl isothiocyanate by procedure A. Scheme 6. Plausible mechanism of dipyrromethane 5 formation during synthesis of pyrrole 4 i from propargylamine 1 b and 2-(vinyloxy)ethyl isothiocyanate.

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Section: Introductionmentioning

confidence: 99%