1,1'-Thiocarbonyldiimidazole (TCDI) | CAS 6160-65-2 | ≥85%

Corey–Winter olefin synthesis — TCDI reacts with vicinal diols to form cyclic thionocarbonates, which undergo syn-elimination upon treatment with trimethyl phosphite or 1,3-dimethyl-2-phenyl-1,3,2-diazaphospholidine to give alkenes with retention of stereochemistry. This two-step deoxygenation is widely used in carbohydrate chemistry and natural product synthesis for the stereocontrolled construction of double bonds from 1,2-diol precursors. The reaction was first reported by Corey and Winter using thiophosgene, but TCDI has largely replaced thiophosgene as the thionocarbonylating agent due to its superior handling safety and selectivity (Corey, E. J.; Winter, R. A. E. J. Am. Chem. Soc. 1963, 85, 2677).

Barton–McCombie deoxygenation — treatment of secondary alcohols with TCDI generates O-imidazolylthiocarbonyl intermediates, which undergo radical-mediated deoxygenation with tributyltin hydride and AIBN to give the corresponding alkanes. This method is one of the most reliable approaches for the selective removal of hydroxyl groups in complex polyhydroxylated natural products and carbohydrates. TCDI offers advantages over alternative thionocarbonylating agents such as carbon disulfide/methyl iodide in terms of selectivity and mildness of reaction conditions (Barton, D. H. R.; McCombie, S. W. J. Chem. Soc., Perkin Trans. 1 1975, 1574).

Thiocarbamate synthesis — TCDI reacts sequentially with alcohols and amines to form thiocarbamates via stepwise displacement of the two imidazole leaving groups. This method provides a mild, selective route to O-alkyl thiocarbamates without the need for thiophosgene or isothiocyanates. The resulting thiocarbamates are useful intermediates in medicinal chemistry and as precursors to radical chain transfer agents (Staab, H. A.; Walther, G. Justus Liebigs Ann. Chem. 1962, 657, 98).

RAFT and MADIX chain transfer agents — trithiocarbonates, xanthates, and dithiocarbamates prepared from TCDI are employed as chain transfer agents in Reversible Addition–Fragmentation Chain Transfer (RAFT) polymerisation and Macromolecular Design via the Interchange of Xanthates (MADIX). TCDI enables the modular construction of these agents from simple alcohol and amine building blocks, providing polymer chemists with a versatile entry point to controlled radical polymerisation mediators with tailored reactivity and solubility profiles.

Thioamide synthesis — TCDI converts primary and secondary amides to the corresponding thioamides under mild conditions. The transformation proceeds via activation of the amide carbonyl as a thiocarbonyl intermediate, followed by loss of imidazole. Thioamides are of interest as isosteric replacements for amides in peptide backbone modifications and as intermediates in heterocycle synthesis (Shalaby, M. A.; Grote, C. W.; Rapoport, H. J. Org. Chem. 1996, 61, 9045).

Enantioselective total synthesis — TCDI has been employed as a key reagent in the total synthesis of complex natural products including (+)-hapalindole Q, 12-epi-fischerindole U, and welwitindolinone A, where it served to construct cyclic thionocarbonate intermediates for subsequent stereoselective olefin formation. These applications demonstrate the reagent’s utility in advanced synthetic sequences requiring functional group tolerance and stereochemical control.