Studies on organophosphorus compounds—XXVIII

Mechanism of the Reaction of Lawesson’s Reagent with N‐Alkylhydroxamic Acids

“…However, the 31 P NMR spectrum of trimer 5 synthesised by an alternative method exhibits the A 2 B spin system [δ P = 72.3 (d, 2 P, J = 49 Hz), 74.4 (t, 1 P, J = 49 Hz) ppm], in accordance with other literature data. [11] Moreover, the presence of trimer 5 in the reaction mixture has finally been excluded after investigating the results of reactions with derivatising reagents. Thus, it has been established that trimer 5 does not react with trimethyl orthoformate (TMOF) at room temperature, while the addition of trimethyl orthoformate to the reaction mixture leads to the disappearance of the signal at δ = 71.4 ppm and quantitative formation of O-methyl phosphonothioate 6 (vide supra).…”

Studies on organophosphorus compounds: Synthesis and reactions of [1,2,4,3]triaza‐phospholo[4,5‐a]quinoxaline derivative

“…2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's reagent, LR, 1) has been shown to be quite versatile in thiation of different carbonyl compounds [15][16][17], and it is also known that nucleophiles attack compound 1 at the phosphorus atom. In certain cases, where the substrate contains two functional groups or can react in different ways, P-heterocycles are formed [18][19][20][21][22]. As an extension of our general studies on the reagent 1, its reaction with quinoxaline derivatives is reported in this work.…”

Synthesis and DNA cleavage evaluation of epoxypiperidine derivatives bearing a dehydroamino acid unit

“…After removal of Alloc group, thiolactam 18 was obtained by heating with Lawesson's reagent. 8 Methylation of 18 using MeOTf afforded the desired thioimidate 7 exclusively without production of N-methyl thiolactam.…”