|Budget Amount *help
¥3,300,000 (Direct Cost : ¥3,300,000)
Fiscal Year 1999 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 1998 : ¥2,100,000 (Direct Cost : ¥2,100,000)
A facile synthesis of sulfur-containing heterocycles by the reaction of the substrates possessing multi-functional groups such as hydroxy, carbonyl and amide with Lawesson's reagent [2,4-bis(p-methoxyphenyl-1,3,2,4-dithiaphosphetane-2,4-disulfide (LR )] is described.
1. Treatment of ω-hydroxy amides with LR in toluene at reflux temperature gave thioenamides, mercapto amides, and sulfur-containing heterocycles, iminothiophene and dithiolactones depending on the number of methylene between hydroxy and amide groups.
2. Treatment of ω-keto amides with equiv. of LR under the same conditions gave the corresponding ω-keto amides, pyrroles, aminothiophenes, and thiopyranes.
3. Thiazine derivatives were obtained by the reaction of 3-N-acylamino alcohol with equiv. of LR. This reaction proceeds stereoselectively. Treatment of 3-N-acylamino alcohols with 0.5 equiv. of LR gave the corresponding N-acylamino thiols, which yielded thiazines by further treatment with 0.5 equiv. of LR.
4. Treatment od N-acylthreonines with LR yielded thiazolinones and oxazolinones.
From above results, the relative reactivity of the functional groups toward LR is considered to be hydroxy > amide > carbonyl > ester.
The reactions of the substrates possessing multi-functional groups with LR described here represent a useful method for the preparation of sulfur-containing heterocycles.