Reaction of acylaminocyanoesters with 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide leading to substituted aminothiazoles. Crysta

2-Acylamino-2-cyanoacetic acid ethyl esters $\text{2a-c}$ react with 2,4-bis (4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane 2,4-disulfide $\text{1}$ in refluxing benzene with formation of 2-alkyl(aryl)-5-aminothiazole-4-carboxylic acid ethyl esters $\text{3a-c}$. Structure $\text{3}$ was established by spectroscopic means and an X ray crystallographic investigation of $\text{3a}$. X-Ray analysis revealed that the thiazole ring, exocyclic nitrogen and carbonyl group forming a hydrogen-bonded cycle are nearly coplanar. A resonance interaction is manifested by distinctly shortened /1.447 (3)/ C_(carbonyl)-C_(thiazole) distance.     

Studies on organophosphorus compounds—XL: Reactions of ketones with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide

Cyclohexanone and cyclopentanone react with 2,4 - bis - 4 - methoxyphenyl) - 1,3,2,4 - dithiadiphosphetane 2,4-disulfide (lawesson Reagent (LR) at 80° with formation of new spiro - 1,3,5,2 - trithiaphosphorines 1 and 2, respectively. 2-Methyl and 2-phenylcyclohexanone also react with LR at 80° producing the enethiols 3 and 4, which on storage are transformed into the sulfides 5 and 6. Unsaturated cyclohexanones 7–9 are transformed into the corresponding thioketones 10–12 after reactions with LR at 60° for a few hours. 2-Hydroxyketones react with LR with formation of 1,3,2-oxathiaphospholes and similarly a 2-aminoketone gave a 1,3,2-thiazaphosphole. Aromatic ketones, reacted with LR to give corresponding thioketones. Thiofluorenone dimerized to form the cyclic disulfide 31, as proved by X-ray analyses.     

Studies on amino acids and peptides-III. 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide,LR, as a new racemization free coupling reagent in peptide synthesis

The easily accessible 2,4-bis (4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4-disulfide, $\text{LR}$, has been reacted with salts of N-protected amino acids $\text{1}$ (Z-Gly-OH, Boc-Gly-OH, Boc-S-Ser(Bzl)-OH, Boc-S-Tyr(Bzl)-OH, Z-S-Arg(Z₂)-OH, and Z-S-Pro-OH), at room temperature in CH₂Cl₂ to give the intermediates $\text{2}$, mixed anhydrides. When $\text{2}$ is treated with two moles of a base and one mole of the salt of an amino acid ester $\text{3}$ (TosOH·H-Gly-OBzl, HCl·H-Gly-OBzl, HCl·H-Gly-OEt, and HCl·H-S-Phe-OtBu) at 0°C, the expected peptide $\text{4}$ is isolated in high yields. LR is also found to be a useful reagent in a fragment coupling between Z-Gly-S-Ala-OH and TosOH·H-S-Leu-OBzl). This tripeptide was tested by means of HPLC (deprotection and amino acid analysis according to Izumiya was not necessary), and no epimerization (<0.7 %) was observed.     

The Reaction of the P-N Bond in Aminophosphines with 2,4-Bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide

Abstract

The reaction of aminophosphines with perthiophosphonicanhydrides by insertion of RPS₂-units into the P-N-bonds, leading to mixed P(III)-P(V)-sulfides, as claimed by a patent*, was reinvestigated using 2,4-Bis-(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (1) and various aminophosphines (2). The results show the insertion to be prevented by steric crowding in the aminophosphines (2), while otherwise mono- (3,4) and diinsertionproducts (5) are quantitatively available by stepwise reaction:     

Studies on amino acids and peptides x : Hplc-mediated test of 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphos-phetane 2,4-disulfide (lawesson's reagent) as a racemization-free coupling reagent

The easily available 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadi-phosphetane 2,4-disulfide (Lawesson's Reagent), 1, has been tested as a coupling reagent for racemization in peptide synthesis. The assay procedure is separation of stereomeric products by HPLC. Z-S-Pro-S-Val-S-Pro-OtBu and Z-S-Leu-S-Phe-S-Val-OtBu have been used as test peptides in 2+1 segment couplings, and only a small amount of epimerization (0.5 and <0.1%, respectively) has been observed.     

2, 4-bis(4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane 2, 4-disulfide,lr, as a new activation reagent in preparation of peptides,amides and esters

Abstract

2, 4-Bis(4-methoxyphenyl)-1, 3, 2, 4-dithiadiphosphetane 2, 4-disulfide, LR, is easily prepared by refluxing P₄S₁₀ in anisole for two hours produces the title compound in high yield.     

Studies on organophosphorus compounds: reactions of benzosuberones with 2,4-bis(p-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide (Lawesson's reagent)

6-Arylidene-3-methyl-6,7,8,9-tetrahydro-5H-benzo[a]cyclohepten-5-ones (2a-h), obtained by the condensation of 3-methylbenzocyclohepten-5-one 1 with appropriate aromatic aldehydes, on reaction with Lawesson's reagent in xylene yielded phosphorus containing compounds 3a-h. A number of these compounds showed promising anti-inflammatory activity.     

Studies on organophosphorus compounds—XXXV: A new route to 4-methoxyphenylphosphonothioic diamides from 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide and amines

By reacting primary and secondary amines with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane-2,4-disulfide, 1A, at 25° ammonium 4-methoxyphenylphosphonamidodithioates, 2, are formed. Upon heating to 140° 2 eliminates hydrogen sulfide in a new type of reaction yielding 4-methoxyphenylphosphonothioic diamides, 3, which also are formed directly from primary amines and 1A at 140°. For dibenzylamine some anomalous results are observed due to N→S rearrangement reactions. NMR spectroscopic data are presented for compounds 2 and 3.     

Synthesis of diarylheptanoids, (5S)-5-acetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-3-heptanone and (3S,5S)-3,5-diacetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane

The total syntheses of the first examples of diarylheptanoid natural products (5S)-5-acetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)-3-heptanone 1, and (3S,5S)-3,5-diacetoxy-1,7-bis(4-hydroxy-3-methoxyphenyl)heptane 2 isolated from the rhizomes of Zingiber officinale were accomplished using Sharpless epoxidation and cross-metathesis reactions as the key steps.     

THE REACTION OF CARBOXYLIC ACID CHLORIDES WITH 2,4-BIS(4-METHOXYPHENYL)-1,3,2,4-DITHIADIPHOSPHETANE 2,4-DISULFIDE

Abstract

Carboxylic acid chlorides react with 2,4-bis(4-methoxyphenyl)-1,3,2,4-dithiadiphosphetane 2,4- disulfide to give the intermediates 2a,b; 2'a,b) which are useful as thioacylating agents. Compounds 2 react with amines under mild conditions to give the corresponding thioamides.     

Reactions of indoles with ortho esters,N,N-dimethylformamide and N,N-dimethylacetamide dialkyl acetals

Indole and N-methylindole react with oxa stabilized carbocations generated in situ from orthoformates to yield tris(3-indolyl)methane. The unsymmetrical isomers, e.g. 2-(N-methyl-3-indolyl)di(N-methyl-3-indolyl)-methane ( 4 ), were not formed as established by an independent synthesis. N,N-Dimethylacetamide dimethyl-acetal reacted with 2-alkyl substituted indoles to produce 1,1-bis(3-indolyl)ethanes ( 3 ).     

The mass spectral rearrangements of 1,6-bis(arylsulfenyl)-2,4-hexadiynes and 1,6-bis(arylsulfonyl)-2,4-hexadiynes

The mass spectral. behavior of 1,6-bis(arylsulfenyl)-2,4-hexadiynes and 1,6-bis(arylsulfonyl)-2,4-hexadiynes were examined. The sulfenyl derivatives extruded the hexadiynyl moiety with the formation of Ar? S? S? Ar fragments. The sulfonyl derivatives, on the other hand, showed no extrusion of the hexadiyne fragment but an expulsion of SO₂ and even two SO₂ units.