Di-2-pyridyl thionocarbonate (DPT) and 1,1``-thiocarbonyldi-2,2``-pyridone are prepared by utilizing 2-hydroxypyridine and thiophosgene, and di-2-pyridyl sulfite is prepared from 2-hydroxypyridine and thionyl chloride.
The reagents are efficient for the direct esterification of carboxylic acids, and di-2-pyridyl sulfite can be used as a dehydrating reagent for the preparation of β-lactams from β-amino acids in high yields. The synthetic utility of the reagents as dehydrating agents has been studied with several aldoximes. Aldoximes are cleanly and rapidly converted into the corresponding nitriles in high yields. Furthermore, di-2-pyridyl sulfite is successfully utilized for the preparation of nitriles and isonitriles from primary amides and formamides, respectively.
The reagents have been found to be very effective for dehydrosulfurization of primary thioamides and N,N``-disubstituted thioureas. Several N,N``-disubstituted thioureas are smoothly converted into the corresponding carbodiimides in high yields. Similarly, primary thioamides are cleanly converted into the nitriles. The preparation and the structure determination of 1,2,4-thiadiazetidin-1-oxide-3-one, a new 4-membered heterocyclic compound, have been accomplished using di-2-pyridyl sulfite.
DPT and 1,1``-thiocarbonyldi-2,2``-pyridone can be utilized as thiocarbonyl transfer reagents for the preparation of isothiocyanates, cyclic thionocarbonates, and 2-oxazolidinethiones from amines, 1,2- and 1,3-diols, and β-amino alcohols, respectively. N-Sulfinylamines are prepared from amines using di-2-pyridyl sulfite as a sulfinylating reagent.
Deoxygenation of alcohols to the corresponding hydrocarbons can be conveniently achieved using 1,1``thiocarbonyldi-2,2``-pyridone. The use of 1,1``-thiocarbonyldi-2,2``-pyridone has been studied for the olefin synthesis from alcohol by pyrolytic elimination and for [3,3]-sigmatropic rearrangement of allylic thionocarbamate.
New amino-protective reagnets, t-buyl S-(2...