[16563-14-7] · C5H5NOS · 4-Cyanothiolan-3-one · (MW 127.11)
Alternate Name: 4-oxothiolane-3-carbonitrile.
Form Supplied in: commercially available.
Alkylation of 4-cyanothiolan-3-one with a variety of alkyl halides in the presence of Potassium Carbonate provides C-alkylated products in excellent yields. Their treatment with aqueous Sodium Hydroxide affords a-substituted acrylonitriles through tandem Dieckmann-Michael retrograde reactions (eq 1).
This rather unstable conjugated diene can be generated and trapped in situ by dienophiles using the nicely crystalline 3-cyano-2,5-dihydrothiophene 1,1-dioxide as a suitable precursor. This precursor is derived from 4-cyanothiolan-3-one in a three-step sequence involving reduction of the carbonyl group followed by dehydration and S,S-oxidation. On heating a toluene solution of the diene in the absence of dienophiles, self-condensation takes place to afford the dimer, which has been hydrolyzed to mikanecic acid (eq 2).
2,5-Dihydrothiophenes, derived from enamines or enol ethers of 4-cyanothiolan-3-one, can be efficiently aromatized to the corresponding thiophene derivatives by treatment with Chloranil3,5 or Sulfuryl Chloride (eq 3).4
The cyclocondensation of 4-cyanothiolan-3-one with 1,2-diaminobenzenes followed by chloranil aromatization affords biologically interesting substituted 10-amino-4H-thieno[3,4-b][1,5]benzodiazepines (1).5
Achille Barco, Simonetta Benetti, & Gian P. Pollini
Università di Ferrara, Italy