Vinyl Thiocyanates Research Articles

Visible-Light-Mediated Decarboxylative Thiocyanation of Cinnamic acids: An Efficient Photocatalytic Approach to the Synthesis of (E)-Vinyl Thiocyanates

A simple and novel methodology for the synthesis of vinyl thiocyanates from decarboxylative cross-coupling reaction of cinnamic acids with KSCN under the synergistic interactions of visible light irradiation, Cs2CO3, Rose Bengal as the photocatalyst and air as the terminal oxidant at room temperature is reported. The reaction takes place by a radical pathway as evidenced from our experiments and literature. The report is the first example on the visible-light mediated thiocyanation of cinnamic acids, which employs environmentally benign and inexpensive starting materials and is characterized by easily removable by-product CO2.

Denitrative thiocyanation of β-nitrostyrenes through visible light photoredox catalysis: An easy access to (E)-vinyl thiocyanates

Eosin Y efficiently catalyzes the aerobic visible light mediated formation of sp2 C-SCN bond through denitrative reaction of β-nitrostyrenes with ammonium thiocyanate in acetonitrile to afford (E)-vinyl thiocyanates in good to excellent yields. Metal-free conditions, use of sustainable resources (visible light and air) and ambient temperature are the exclusive attributes of the present protocol.

C4‐Selective Synthesis of Vinyl Thiocyanates and Selenocyanates Through 3,4‐Dihalo‐2(5H)‐furanones

In the absence of a metal catalyst and under the promotion of sodium bicarbonate, an eco‐friendly and practical protocol for the synthesis of vinyl thiocyanate derivatives through the reaction of 3,4‐dihalo‐2(5H)‐furanones with KSCN at room temperature has been developed. This method has a broad substrate scope and is suitable for gram‐scale synthesis (up to 5 g). Importantly, it can also be used to synthesize vinyl selenocyanate derivatives.

Homogeneous and Nanoparticle Gold-Catalyzed Hydrothiocyanation of Haloalkynes.

The first homogeneous and heterogeneous nanoparticle gold-catalyzed addition of sulfur nucleophiles to alkynes was developed. More specifically, gold-catalyzed hydrothiocyanation of haloalkynes gave good yields and good stereoselectivity of vinyl thiocyanates. Furthermore, a sulfur-based gold catalyst (PPh3AuSCN) has shown a unique reactivity in gold-catalyzed reactions such as the cyclization of N-propargylic amides.

Electrosynthesis of ( E)-Vinyl Thiocyanates from Cinnamic Acids via Decarboxylative Coupling Reaction.

Thiocyanate compounds are key intermediates in the synthesis of pharmaceuticals and other sulfur-containing organic compounds. Herein, we first report an electrochemical protocol to synthesize vinyl thiocyanates from decarboxylative coupling of cinnamic acids with NH4SCN in aqueous solution. This method provides thiocyanation products with broad functional group tolerance under ambient conditions.

Silver‐Catalyzed Regio‐ and Stereoselective Thiocyanation of Haloalkynes: Access to (Z)‐Vinyl Thiocyanates

AbstractA regio‐ and stereoselective method for the preparation of (Z)‐vinyl thiocyanate derivatives by silver‐catalyzed thiocyanation of haloalkynes is reported. This method features practical, free of ligand, broad substrate scope, excellent stereoselectivity and gram‐scale synthesis. Significantly, the halogen atom of haloalkynes is retained, which allows the synthesis of 2,5‐diphenylthiophene, thiazol‐2‐amine and trifluoromethyl sulfides derivatives via simple transformation.magnified image

ChemInform Abstract: Rearrangement Reactions. Part 9. Synthesis of New Vinyl Thiocyanates by [3,3]Sigmatropic Rearrangement of Isothiocyanates.

AbstractChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Synthesis of New Vinyl Thiocyanates by [3,3] Sigmatropic Rearrangement of Isothiocyanates

Propargyl isothiocyanates 3 and buta-2,3-dienyl isothiocyanates 20 were prepared conventionally from amines and thiophosgene, or by a new, one-pot procedure using nucleophilic substitution to generate azides, which in turn served as the starting materials for a Staudinger reaction, followed by treatment of the resulting iminophosphoranes or iminophosphates with CS2. Equilibration, through a [3,3] sigmatropic rearrangement, of 3 and the allenyl thiocyanates 4 was established by flash vacuum pyrolysis or by thermolysis in solution. Even the reversible isomerization of the parent compounds 3f and 4f favors the allenyl thiocyanate. In the case of 20, an irreversible rearrangement reaction gave high yields of 2-thiocyanatobuta-1,3-dienes 21. A sequence of two [3,3] migration steps transformed 1,4-diisothiocyanatobut-2-ynes 3m and 3n into 2,3-dithiocyanatobuta-1,3-dienes 21m and 22, respectively. These reactions demonstrate that the [3,3] sigmatropic rearrangement of mustard oils, to afford high yields of thiocyanates bearing the thermodynamically less stable functional group, is possible if the conversion gives rise to a more stable carbon skeleton. The equilibration of 1-thiocyanatopent-2-en-4-ynes 12 and 1-thiocyanatopenta-1,2,4-trienes 14 could be explained by tandem [3,3]−[3,3] sigmatropic rearrangements through short lived 3-isothiocyanatopent-1-en-4-ynes 13. Thiocyanato-substituted vinylallenes 4k and 14 tended to electrocyclize to give cyclobutenes 7 and 15, respectively. Thiocyanates 21a, 21b, 21m and 14a, which exhibit a buta-1,3-diene structure, could be used in Diels−Alder reactions to afford the cycloadducts 25a, 25b, 26a, 26m, 28m, 29m, and 30.

Addition de l'acide thiocyanique aux acetyleniques a l'aide de hg(II) II - Obtention d'isothiocyanates vinyliques par mercuration-protodemercuration

Thiocyanic acid HSCN is added to some acetylenic compounds R 1-C& 2 through a two-step one-pot procedure wich involves, first, the generation in CH 2Cl 2 of β-thiocyanato and/or β-isothiocyanato alkenyl mercuric coupounds R 1-C (SCN)=CR 2-Hg- by addition of mercury (II) thiocyanate Hg(SCN) 2 to R 1-C& 2 then the substitution of mercury by hydrogen through acidic treatment. In proper conditions of stoechiometry and reaction time the process is tharmodynamically controlled and thus allows to obtain vinyl isothiocyanates R 1-C(-NCS)CHR 2 even when the isomeric vinyl thiocyanates are kinetically favoured. Preparation of 3,3- dimethyl 2-isothiocyanato 1-thiocyanato 1-butene is also reported.

ChemInform Abstract: REACTION OF PHOTOGENERATED VINYL CATIONS WITH AMBIDENT ANIONS

AbstractDie Photolyse der Triarylvinylbromide (1) in Gegenwart von KOCN im Zweiphasensystem liefert die Isochinolinone (II).

A comparative multinuclear 1H, 13C, and 15N magnetic resonance study of organic thiocyanates and isothiocyanates

1 H, 13C, and 15N n.m.r. spectra of thiocyanato (RSCN) and isothiocyanato (RNCS) compounds, especially for the vinylic series R1C(SCN)=CHR2 and R1C(NCS)=CHR2, are reported. 15N Chemical shifts of thiocyanates (δca.–100 p.p.m.) and of isothiocyanates (δca.–275 p.p.m.) are very different, the value for the thiocyanate ion (SCN)– being intermediate (δ–165 p.p.m.). Comparison of the spectra of vinyl thiocyanates and isothiocyanates with those of the corresponding saturated compounds suggests that the SCN group exerts both attractive σ and π effects on the CC bond mainly through the intervention of the d orbitals of the S atoms. The NCS group appears to be slightly electron donating towards the double bond. Solvent effects on the 15N chemical shift of BunSCN and BunNCS are discussed in terms of Taft's linear solvation energy relationships.

REACTION OF PHOTOGENERATED VINYL CATIONS WITH AMBIDENT ANIONS

Abstract Photolysis of vinyl bromides with cyanate anion In a two-phase system gave only isoquinolinones as the N-site attacked products. However, the photolysis with thiocyanate anion gave both the N-site attacked products, isothioquinolinones or vinyl isothiocyanates, and the S-site attacked products, vinyl thiocyanates.