C-metallierung an phosphaaromaten - 2-lithio-1-methyl-1,3-benzazaphosphol

1-Methyl-1,3-benzazaphospholes are described; the 2H derivate and t-BuLi give the title compound, characterized by reaction with CO₂ and Me₃SiCl; NMR data confirm the results.     

Synthesis,thermochemistry, and structural characterization of organoruthenium arene and triene complexes

The synthetic, thermodynamic and structural investigations of organoruthenium complexes of the form Cp^*Ru(triene)OTf (Cp^*=n⁵-(CH₃)₅C₅; triene=anisole 1, indole 2, cycloheptatriene 3, OTf=OSO₂CF₃) are presented in this contribution. A direct entryway into the thermochemistry of these complexes is made possible by the rapid and quantitative arene/triene substitution for the three acetonitrile ligands in Cp^*Ru(CH₃CN)₃OTf. The solution calorimetric study establishes the following order of stability: cycloheptatriene < anisole < indole. This study helps clarify the enthalpic and entropic components to the thermodynamic driving forces behind the formation of ruthenium arene/triene complexes. The solid-state structures of these three complexes(1–3) were determined by X-ray single-crystal studies. Thermodynamic factors affecting the Ru-triene bond energy are compared with structural results for these three ruthenium complexes.     

Studies on the highly regio- and stereoselective selenohydroxylation of 1,2-allenylic sulfoxides with PhSeCl

The selenohydroxylation of 1,2-allenyl sulfoxides with PhSeCl in MeCN/H₂O (10/1) afforded E-3-hydroxy-2-phenylseleno-1-alkenyl sulfoxides in good yields and high regio-/stereoselectivities.     

Dianion of sulfinylacetone as a synthetic equivalent of beta-enolate of propionic acid: a novel synthesis of carboxylic acids from alkyl halides with three-carbon elongation

The reaction of the dianion of phenylsulfinylacetone with alkyl halides afforded beta-keto sulfoxides, which were first chlorinated with hexachloroethane and then treated successively with KH and t-BuLi to give carboxylic acids in three-steps in moderate overall yields from the alkyl halides. This procedure affords a good method for a synthesis of carboxylic acids from alkyl halides with three-carbon elongation.     

Synthesis of rodocaine

A new method for synthesis of rodocaine (1) is presented. Two key steps were carried out by the N-bromosuccinimide (NBS)-mediated intermolecular addition of known enamine 5 with allyltrimethyl silane in presence of boron trifluoride etherate (BF₃/OEt₂) and the intramolecular ring-closing metathesis of triene 3. The Diels-Alder cycloaddition of triene 3 with different ethyl propiolates was also studied.     

Highly regio- and stereoselective PdCl2(MeCN)2-catalyzed cross coupling of 1,2-allenylic sulfoxides with allyl bromide

2-Allyl-1(E),3(E)-dienyl sulfoxides were prepared highly stereoselectively via the PdCl₂(MeCN)₂-catalyzed coupling reaction of 1,2-allenylic sulfoxides and allyl bromide. A rationale was proposed for this transformation.     

Facile and Selective Oxidation of Sulfides to Sulfoxides by t-Butyl Hydroperoxide in Aqueous Medium

The oxidation of sulfides to sulfoxides with TBHP in water only occurs selectively with high yields and permits the sulfoxides to be prepared without using organic solvents. When the reaction is performed in aqueous sulfuric acid with a H₂SO₄/sulfide molar ratio of 20/1, the oxidation rate is greatly increased.     

Sulfoxide-controlled SN2′ displacements between cuprates and vinyl and alkynyl epoxy sulfoxides

The S_N2′ displacement of readily available vinyl epoxy sulfoxides with organocopper reagents takes place in good yields with high anti selectivity and a good degree of E/Z stereocontrol to produce enantiopure α-hydroxy vinyl sulfoxides. A second allylic displacement on the related mesyloxy vinyl sulfoxides allows for the asymmetric construction of two adjacent chiral centers. In addition, cuprate mediated S_N2′ addition to alkynyl epoxy sulfoxides affords α-hydroxy allenyl sulfoxides in good yields.     

Supermesityl-stabilisierte Iminoborane

Supermesityl stabilized Iminoboranes Amino-iminoboranes R′(SiMe₃)N–B≡N–R: IIc (R′ = CHMe₂), IId (R′= CMe₃) and IIe (R′ = SiMe₃) carrying the supermesityl group (R) on the imino nitrogen atoms have been prepared from the corresponding fluorobis(amino)boranes Ic–e by HF-elimination using t-BuLi (IIc, d) or n-lithio-bis(trimethylsilyl)amid (IIe) . The Amino-iminoboranes are thermally stable at room temperature. Upon treatment of the fluorobis(amino)boranes Ia, Ib, Ie with t-BuLi, LiF and HN(SiMe₃)R′ are eliminated and the B-t-butyl substituted iminoborane III is formed. The compounds are characterized by elementar analyses and spectroscopic data (MS, IR, NMR). An X-ray diffraction study has been performed for II d .     

Mechanisms of addition of primary aromatic amines and cyclohexylamine to tricarbonyl(cycloheptatrienyl)tungsten cation

X-substituted anilines (X = H, 2-Me, 4-Me or 2-Cl) and cyclohexylamine are shown to add to the tropylium ring of cation [(η)-C₇H₇)W(CO)₃]⁺ to give the corresponding ring adducts of tricarbonyl(cyclohepta-1,3,5-triene)tungsten. Kinetic studies have demonstrated that the anilines form the triene ring adducts via the rapid pre-equilibrium formation of a π-complex, which rearranges in a rate-determining fashion to form a cationic triene intermediate [(1–6-η-C₆H₇.NH₂R)-W(CO)₃]⁺ (R = C₆H₅, 2-MeC₆H₄, 4-MeC₆H₄ or 2-ClC₆H₄); from this the final product is rapidly formed via amine- or solvent-assisted proton loss. With the aliphatic cyclohexylamine, the cationic triene intermediate is formed directly, followed by competing rate-determining solvent- and amine-assisted proton removal.     

Development of new synthetic methods with aryl 1-chlorovinyl sulfoxides

Aryl 1-chlorovinyl sulfoxides were easily synthesized from ketones and aldehydes with aryl chloromethyl sulfoxide in three-steps with high overall yields. Low-temperature treatment of the aryl 1-chlorovinyl sulfoxides with alkyllithium or a Grignard reagent gave alkylidene carbenoids via a sulfoxide-metal exchange reaction. From the alkylidene carbenoids, acetylenic compounds, tetra-substituted olefins, and allenes were synthesized. Enolization of alpha-chloro alpha-sulfinyl ketones, which were synthesized from methyl esters and chloromethyl phenyl sulfoxide, is another method for the generation of aryl 1-chloroalkyl sulfoxides. Treatment of 1-chlorovinyl phenyl sulfoxides so generated with t-BuLi followed by some nucleophiles having an acidic hydrogen gave one-carbon elongated carboxylic acids and their derivatives. Conjugate addition of some carbanions with 1-chlorovinyl p-tolyl sulfoxides was found to have taken place. For example, reaction of 1-chlorovinyl p-tolyl sulfoxides with cyanomethyllithium gave high yields of cyclic enaminonitriles. Acidic treatment of the enaminonitriles afforded good yields of 4,4-disubstituted 2-cyclopentenones. By using unsymmetrical ketones and optically pure chloromethyl p-tolyl sulfoxide, this procedure suggests a good method for an asymmetric synthesis of optically pure 4,4-disubstituted 2-cyclopentenones. This method achieved an asymmetric total synthesis of (+)-alpha-cuparenone starting from methyl 4-methylphenyl ketone and (R)-(-)-chloromethyl p-tolyl sulfoxide. A novel synthesis of 2,4,4-trisubstituted 2-cyclopentenones is also successful using cyanomethyllithium and its homologues. Conjugate addition of the lithium enolate of tert-butyl acetate and its homologues gave high yields of the adduct, 3,3-disubstituted esters. Synthesis of various kinds of carboxylic acids and their derivatives and lactones was realized from the adducts.     

Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl-pyrazolone-5 (HPMBP) and some long chain aliphatic sulfoxides

Synergistic extraction of uranyl ion with 1-phenyl-3-methyl-4-benzoyl pyrazolone-5 (HPMBP) and aliphatic sulfoxides of varying basicities, viz di-isoamyl (DIASO), di-n-hexyl (DHSO), di-n-septyl (DSSO), di-n-octyl (DOSO), di-n-nonyl (DNSO), di-n-decyl (DDSO) or di-n-undecyl (DuDSO) sulfoxide has been studied at 30±0.1°C. Extraction with some of these sulfoxides has been studied at various fixed temperatures also. The organic phase equilibrium constant (log Ks) has been found to increase with the basicity of the sulfoxide up to DOSO beyond which there is a gradual decreasing trend which has been attributed to the effect of possible steric hindrance (spatial) involved in the bonding of the higher sulfoxides (greater than 8 carbon atoms) with UO₂ (PMBP)₂ chelate. This has been supported by thermodynamic data involved in these systems. The entropy values for sulfoxides with eight or more carbon atoms are much more negative as compared to the lower sulfoxides and are also in contrast to HTTA and BTFA systems with these sulfoxides studied earlier.     

Synthesis and equilibrium studies of new dihydrothiophene sulfoxides

Oxidation of the Knoevenagel condensation products 2 of 3-oxo- tetrahydrothiophene (1) and active methylene compounds of the type Z-CH₂-COOH with an H₂O₂/V₂O₅/t-BuOH reagent furnishes the corresponding sulfoxides 3 in excellent yields. The isomer distributions of the sulfides 2 and the sulfoxides 3 reflect peculiarities of hydrothiophenes as compared to similar open-chain systems and establish that the stabilizing effect of the sulfoxide group on β, γ-double bonds is greater than the corresponding effect of so strongly stabilizing groups as CN and COOR.     

Highly efficient rhenium-catalyzed deoxygenation of sulfoxides without adding any reducing agent

This work reports a novel method for the deoxygenation of aromatic and aliphatic sulfoxides catalyzed by oxo-rhenium complexes without adding any reducing agent. The oxo-rhenium complex ReOCl₃(PPh₃)₂ proved to be very efficient for the deoxygenation of several sulfoxides with tolerance of different functional groups.     

一种用于光催化氧化硫醚成亚砜的超薄卟啉的共价有机骨架纳米片

单线态氧(~1O_2)可将硫醚化合物选择性氧化为亚砜,而开发具有高~1O_2量子产率的高效光敏剂至关重要。本文中我们报道了超薄二维共价有机骨架(COFs)纳米片(NSs)COF-367 NSs的制备和表征。COF-367 NSs在各种有机溶剂中的良好分散性和高效率的光收集赋予其在可见光照射下产生~1O_2的显著性能,且远优于块体COF-367。我们还证明了COF-367 NSs是硫醚化合物光催化氧化成亚砜的优良非均相催化剂,具有高效率和选择性以及良好的循环稳定性。     

Microbial reduction of sulfur-containing ketones by Geotrichum sp.

Bioreduction of some β-carbonyl phenyl sulfides, sulfoxides and sulfones (1, 3, 5, 8, 11 and 13) by Geotrichum sp. was studied. Reduction of β-carbonyI phenyl sulfoxides (5 and 8) gave anti-Prelog sulfoxide alcohols. (S, Ss)-3-Chloro-1-phenylsulfinylpropan-2-ol (9) was obtained in high yield with 95% e. e. after recrystallization from methylene chloride-petroleum ether.     

Highly efficient and chemoselective reduction of sulfoxides using the system silane/oxo-rhenium complexes

This work reports a novel method for the reduction of sulfoxides with silanes catalyzed by high valent oxo-rhenium(V) and (VII) complexes. The catalytic system PhSiH₃/ReIO₂(PPh₃)₂ (1 mol %) proved to be highly efficient for the reduction of a wide range of sulfoxides in excellent yields under mild conditions. This novel methodology is also highly chemoselective, tolerating several functional groups such as –CHO, –CO₂R, –Cl, –NO₂, and double or triple bonds.     

Synthesis of enantiomerically pure 2-amino alcohols from amino acids mediated by sulfoxides

Enantiomerically pure (R₁,S₂)- and (S₁,S₂)-2-amino alcohols can be easily synthesized by stereodivergent reduction of α′-(N-Boc)amino β-keto sulfoxides (easily synthesized from readily available N-Boc amino ester hydrochlorides) with DIBAH (de 82–92%) and DIBAH/ZnBr₂ (de 80%), followed by hydrogenolysis of the C–S bond of the resulting hydroxy sulfoxides and final hydrolysis of the N-Boc protecting group.     

BF3·OEt2-catalyzed intermolecular reactions of arylmethylenecyclopropanes with (E)-1,1,3-triarylprop-2-en-1-ols

BF₃·OEt₂-catalyzed intermolecular reactions of arylmethylenecyclopropanes with (E)-1,1,3-triarylprop-2-en-1-ols produced the corresponding triene compounds, alcoholic derivatives or cyclobutane derivatives in moderate to excellent yields under mild conditions.     

An Autocatalytic System of Photooxidation‐Driven Substitution Reactions on a FeII4L6 Cage Framework

The functions of life are accomplished by systems exhibiting nonlinear kinetics: autocatalysis, in particular, is integral to the signal amplification that allows for biological information processing. Novel synthetic autocatalytic systems provide a foundation for the design of artificial chemical networks capable of carrying out complex functions. Here we report a set of Fe^II₄L₆ cages containing BODIPY chromophores having tuneable photosensitizing properties. Electron‐rich anilines were observed to displace electron‐deficient anilines at the dynamic‐covalent imine bonds of these cages. When iodoaniline residues were incorporated, heavy‐atom effects led to enhanced ¹O₂ production. The incorporation of (methylthio)aniline residues into a cage allowed for the design of an autocatalytic system: oxidation of the methylthio groups into sulfoxides make them electron‐deficient and allows their displacement by iodoanilines, generating a better photocatalyst and accelerating the reaction.