Alkylthio Substituents Research Articles

Influence of steric crowding at the heteroatom on the metathesis of functionalized olefins: the polymerization of alkylthiocyclooctenes catalyzed by a metallacyclic aryloxo(chloro)neopentylidenetungsten complex

The ring-opening metathesis polymerization of various alkylthiocyclooctenes was successfully carried out in the presence of a metallacyclic aryloxo (chloro)neopentylidenetungsten complex. The polymerization rates depend strongly on the steric crowding of the alkylthio substituent which confirms that coordination of the heteroatom to the metal is one of the important factors that govern the rate of the metathesis of this type of functionalized olefin.

ChemInform Abstract: Preparation and Oxidative Doping Studies of α,ω‐Dithienyl Polyenes Stabilized by Long Chain Alkylthio Substituents.

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Inter‐ and intramolecular hetero diels‐alder reactions, 39. Influence of phenylthio and alkylthio substituents on the reactivity of 1‐Oxa‐1,3‐butadienes in hetero diels‐alder reactions

AbstractThe synthesis of the cyclic enamino ketones 1–3 bearing an alkylthio or an phenylthio group and their reactivity in hetero Diels‐Alder reactions with enol ethers is described. Only compound 3 with an phenylthio group undergoes a cycloaddition with 16a–d to afford the diastereomeric adducts 17a–d and 18a–d. To estimate the activation by a phenylthio and alkylthio group semiempirical PM3/RHF calculations of the frontier orbital energies and coefficients of different enamine carbaldehydes have been performed.

Acid-Promoted Reactions of Schiff’s Bases with Ketene Dithioacetal, Vinyl Sulfides, and 1,2-Propadienyl Sulfides

Abstract Several types of addition reactions proceed between Schiff’s bases and olefinic nucleophiles containing an alkylthio substituent. Ketene dithioacetal or 2-(methylthio)allylsilane reacts with Schiff’s bases in the presence of trifluoromethanesulfonic acid to afford β-amino acid equivalents or homoallylic amines, respectively. On the other hand, ene reaction proceeds between 1-alkyl-1,2-propadienyl sulfides and Schiff’s bases by treatment with AlCl3, giving 1,3-dienes.

Synthesis and antimicrobial activity of N-[5-(4- t-amino-2-butynyl)thio-1,3,4-thiadiazol-2-yl]-2-carbamates

Three series of 5-thio-1,3,4-thiadiazole carbamates containing alkynyl, aminoalkynyl, alkenyl or alkyl thio substituents have been synthesized as potential antimicrobial agents. The influence of both the alkynyl linkage and the various terminal nitrogen heterocyclic moieties on antimicrobial activity was assessed utilizing representative Gram-positive, Gram-negative and fungal species. Mannich base analogs containing a 2-ethyl carbamate group and a nitrogen heterocyclic of limited bulk provided the broadest spectrum of antimicrobial activity. The thiadiazole carbamates containing a 5-alkylthio substituent were consistently active against the Pseudomonas and Candida organisms studied. It is concluded that an acetylenic linkage is not an absolute requirement for potent antimicrobial activity in this molecular series, and that the binding sites of the organisms tested exhibit a steric requirement for lipophilic, but non-bulky, amine-containing heterocycles on Mannich base analogs.

Preparation and oxidative doping studies of α,ω-dithienyl polyenes stabilized by long chain alkylthio substituents

Polyenes containing mesomerically interactive substituent groups can be oxidatively doped with SbCl5 in solution to yield stabilized bipolaron-like charge states. However, in both α,ω-diphenyl and α,ω-dithienyl polyene series, lack of solubility has precluded studies of bipolaron formation for polyenes containing more than six double bonds in the polyene segment. In the present study, the use of long-chain alkylthio substituents to stabilize the bipolaronic charge states has allowed the synthesis of dithienyl polyenes containing up to ten double bonds, and observation of bipolaron formation in the octaene. Models for copolymers containing these bipolaronic repeat units have also been synthesized, and oxidatively doped.

New radical cation salts of substituted pyrenes

Pyrenes with alkylthio substituents represent a new class of relatively cheap donor compounds which can be reacted to very stable radical cation salts with high conductivity (up to 677 S/cm).

A facile preparation of tetrathiafulvalenes having alkylthio groups from 1,3-dithiole-2-thiones using a high-pressure reaction

Tetrathiafulvalenes such as bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF) having alkylthio substituents have been prepared in good yields by direct desulphurization of 1,3-dithiole-2-thiones with trimethyl phosphite under high pressure.

Tetrakis(alkylthio)thieno[3,4‐c]thiophene: Synthesis, stability, and reactivity

AbstractThe synthesis of tetrakis(alkylthio)thieno[3,4‐c]thiophenes la‐e by the dimerization reaction of bis(alkylthio)cyclopropenethiones is described. The remarkable thermodynamic and kinetic stability suggests the significant electron‐accepting conjugation of the alkylthio substituents to the carbanionic 1, 3, 4, and 6 carbons in the framework. The isopropylthio‐ and ethylthio‐substituted thienothiophenes 1d and 1e undergo cycloaddition reactions with dienophiles such as N‐phenylmaleimide and dimethyl acetylenedicarboxylate to give the cycloadducts in moderate yields.

Structure and absolute stereochemistry of thioacetal sulphoxides obtained by fungal metabolism of 2-alkyl-1,3-dithianes

Monosulphoxide metabolites of 2-methyl-, 2-t-butyl-, 2,2-dimethyl-, and 2-methyl-2-t-butyl-1,3-dithiane have been isolated after addition of the thioacetals to growing cultures of the fungi Aspergillus foetidus, Mortierella isabellina and a Helminthosporium species. The optical yields of the chiral monosulphoxide metabolites (0–72%) were determined by n.m.r. analysis in (–)-phenyl- or 1-(+)-9-anthryl-2,2,2-trifluoroethanol–CDCl3, solvent mixtures. The signs of Cotton effects obtained from c.d. spectra have been used to assign the absolute stereochemistry of the chiral thioacetal sulphoxides. Optically pure samples of 2,2-dimethyl-1,3-dithiane 1-oxide, cis-2-methyl-1,3-dithiane 1-oxide, and trans-2-methyl-1,3-dithiane 1-oxide, have been obtained by a chemical resolution method which provides confirmation of optical yields and absolute stereochemistry.The fungal metabolism results indicate that the mono-oxygenase enzymes can stereo-differentiate between prochiral (diastereotopic) lone pairs on a sulphur atom and also between prochiral (enantiotopic) thioalkyl substituents on a carbon atom during the formation of monosulphoxides.

Tricoordinate Silicon Ion Prepared in Solution

A long-sought organic intermediate—the silylenium ion (R 3 Si + )—has been prepared in solution for the first time by Northwestern University chemistry professor Joseph B. Lambert and graduate student William J. Schulz Jr. [ J. Am. Chem. Soc. , 105 , 1671 (1983)]. Evidence has been presented for the existence of the silylenium ion in the gas phase, Lambert says, but numerous efforts to prepare it in solution have failed. He points out that the analogous carbenium ion (R 3 C + ) also is less stable than the common tetracoordinate form; however, carbenium ions can be stabilized by 2p-3p resonance. In contrast, the silylenium ion is more weakly stabilized by 2p-3p overlap, over longer bond distances. The chemists' strategy was to stabilize the silylenium ion by the use of alkylthio substituents. They turned to sulfur because of its high polarizability, its low electronegativity, and the possibility that the 3p-3p overlap would be more effective than 2p-3p overlap. Lambert notes that the leaving group proble...

Sodium‐Ammonia Reductions in N‐Heteroaromatic Chemistry. Protodehalogenation and Protodealkylation of Sulphur Containing Pyrimidines, Pyridazines and S‐Triazines

AbstractThe Birch reduction of chloro‐pyrimidine, ‐pyridazine and ‐s‐triazine derivatives bearing a prototropic substituent gives the corresponding dehalogenated compounds in good yields. Methylthio‐ and ethylthio‐substituents undergo a reductive cleavage: 4‐amino‐6‐methylthiopyrimidine (II) and 2,4‐bis‐diethylamino‐6‐ethylthio‐s‐triazine (III) are converted to the corresponding mercapto compounds. Moreover, the sodium‐ammonia reagent is able to remove a chlorine atom from a molecule containing a mercapto or alkylthio substituent; the efficiency of this reaction is shown by the one step reduction of 4‐amino‐6‐chloro‐2‐methylthiopyrimidine (VI) and 3‐chloro‐6‐mercaptopyridazine (VII) to the corresponding dehalogenated mercaptans in 66 and 58% yield, respectively.

Anticholinesterase properties of O-ethyl S-(?-phenylalkyl)methylthiophosphonates

1. A series of O-ethyl S-(ω-phenylalkyl)methylthiophosphates was synthesized. 2. The anticholinesterase activity of the synthesized compounds depends strongly on the distance of the phenyl group in the alkyl thio substituent from the phosphorus atom.

Insecticidal carbamoyloximes

A review of the salient features of the activity of carbamoyloximes, the newest category of insecticidal and acetylcholinesterase-inhibiting carbamates, shows their marked resemblance to the carbamates of cyclic enols and of phenols. The electronic effect of substituents on anticholinesterase activity is more obvious for the carbamoyloximes than it is for the carbamates of phenols. Alkylthio substituents appear to affect activity directly by increasing the affinity for acetylcholinesterase and indirectly through their potential for sulphoxidation. Although carbamoyloximes as a class are active against all major types of insect pest, individual compounds usually are highly selective. Much of this selectivity is probably the the result of detoxification. Methylenedioxyphenyl derivatives synergise many of these carbamates against the housefly. The rǒle of physical properties in determining penetration, detoxification, synergism, and systemic action is discussed with special reference to ‘Temik’ (2-methyl-2 methylthiopropionaldehyde O-(methylcarbamoyl)oxime) and its oxidation products.