Aromatic Biheterocycles: Syntheses, Structures, and Properties

Butanone side chains at arenes and hetarenes, efficiently introduced by a Heck-type reaction, are transformed to annulated thieno[3,2-b]thiophenes in a domino redox process under Willgerodt-Kindler conditions. A nucleophilic aromatic substitution with an intermediary thioenolate is a reasonable key step of this process.

A domino annulation reaction under Willgerodt-Kindler conditions

In this review the chemistry of sulphur-containing oxalic acid derivatives is summarized from the synthetic point of view. Thiooxalic acid derivatives can be prepared in the following ways: transformation of oxalic acid derivatives oxidation of C2 compounds, mainly derivatives of haloacetic acids formation of C[sbnd]C bonds between C1 compounds Thiooxalic acid derivatives are active and useful C2 synthons. The incorporation of sulphur atoms in oxalic esters increases their reducibility. 1,1-Dithiooxalic acid esters and amides, dithionooxalic acid esters, and, especially, tetrathiooxalic acid dimethyl ester are attacked by S- and C-nucleophiles at the thiono group (thiophilic attack) to form the oxidation stage of a thioaldehyde or sulphides, respectively. In cycloaddition reactions oxalic acid derivatives with one thiono function react as 2π-systems whereas dithiono- and tetrathio-esters may function as 2π- as well as 4π-systems. In comparison to their O-analogues thionooxalic acid derivatives po...

Darstellung und Reaktionen von Thiooxalsäuren und Thiooxalsäurederivaten

3,6-Bis(p-dimethylaminophenyl)-1,2-dithiin versus 3,4-Bis(p-dimethylaminophenyl)-1,2-dithiete – A Mechanistic Probe for the Photoinduced Behavior of the 1,2-Dithiin System©

Die Kondensation von 2-Morpholino- bzw. 2-Piperidino-dithiooxalsaure-O-ester 1 mit Malondinitril oder Cyanessigester in Gegenwart von Kaliumethanolat fuhrt zu den Kaliumsalzen 3, die sich mit Alkyliodiden zu den Thioenolethern 4 alkylieren lassen. Bei Einsatz von CH-aciden Alkylierungsmitteln entstehen unmittelbar die Thiophene 6. 3a cyclisiert mit Hydroxylaminsulfonsaure zum Isothiazol 8, 4 mit Hydrazin zu den Pyrazolen 10.S-Alkylierung der Thiophene 6 am Thioamid-Schwefel und nachfolgende Hydrazinolyse liefert die Thiopheno[2.3-d]pyridazine 13 und 14.



Thiono- and Dithioesters XXXIX: Condensation of 2-Morpholinodithiooxalic O-esters with Malonodinitrile or Cyanoacetate



Condensation of 2-morpholino- or 2-piperidino-dithiooxalic O-esters 1 with malonodinitrile or cyanoacetate in the presence of potassium ethanolate leads to the formation of the potassium salts 3, which are alkylated by alkyl iodides to give the thioenol ethers 4. With CH-acidic alkylating agents the thiophenes 6 are obtained directly. Compound 3a cyclises with hydroxylamine-O-sulfonic acid to form the isothiazole 8; compound 4 with hydrazine yields the pyrazoles 10.S-Alkylation of the thiophenes 6 at the thioamide sulfur followed by hydrazinolysis gives the thiopheno[2.3-d]pyridazines 13 and 14.

Thion‐ und Dithioester, 39. Mitt. Zur Kondensation von 2‐Morpholino‐dithiooxalsäure‐O‐ester mit Malondinitril oder Cyanessigester

Dithionoxalsaureester 1 reagieren mit primaren aliphatischen und aromatischen Aminen in Ather zu den N,N′-disubstituierten Dithiooxamiden 3, in verd. alkohol. Losungen liefern primare aromatische Amine bevorzugt Iminoester wie 6 oder 7. 1 bildet mit o-Aminophenolen und -thiophenolen die 2,2′-Bibenzox- (bzw. thi-)azolyle 9 und mit o-Phenylendiamin die 2,3-Dialkoxychinoxaline 11. Sekundare aliphatische Amine reagieren mit 1 im 1. Schritt zu den 2-Dialkylamino-dithiooxalsaure-O-estern 12 sowie 13 und bei erhohter Temperatur zu den N,N,N′,N′-Tetraalkyldithiooxamiden 14. Die Umsetzung von 12 mit primaren aliphatischen Aminen liefert N,N,N′-Trialkyldithiooxamide 15. Beim Erwarmen in Pyridin lagert 12 zu den Thiolestern 16 um, die ihrerseits mit primaren aliphatischen Aminen N,N,N′-trisubstituierte Monothiooxamide 17 bilden.



Reaction of Dithionooxalic Esters with Amines.



Dithionooxalic esters 1 react with primary aliphatic and aromatic amines in ether to form the N,N′-disubstituted dithiooxamides 3; in dilute alcoholic solutions primary aromatic amines yield preferentially the iminoesters 6 or 7. Condensation of 1 with o-aminophenol and o-aminothiophenol gives the 2,2′-bibenzox-(or thi-)azolyls 9, and with o-phenylendiamine the 2,3-dialkoxyquinoxalines 11. Secondary aliphatic amines react with 1 to form in the first step the 2-dialkylamino-dithiooxalic-O-acid esters 12–13 and at higher temperatures the N,N,N′,N′-tetraalkyl dithiooxamides 14. Condensation of 12 with primary aliphatic amines leads to the N,N,N′-trialkyl dithiooxamides 15. By heating in pyridine 12 rearranges to the thiolesters 16, which react with primary aliphatic amines to form the N,N,N′-trisubstituted monothiooxamides 17.

K. Hartke

Papers

Thion‐ und Dithioester, 17. Mitt.: Über die Reaktion von Dithionoxalsäureestern mit Aminen