New conjunctive reagents as cross-coupling partners en route to retinoid-like polyenes

[structure: see text] New conjunctive reagents E-2 and Z-3 can be used, after transmetalation, in Negishi couplings with vinyl and aryl iodides. The subsequently unmasked terminal alkynes can be further manipulated to arrive at retinoid-like products.     

Simultaneous hydrosilation and ring-opening polymerization as a route to novel polymer architectures

Typical platinum, rhodium and cobalt hydrosilation catalysts have been found to catalyze the ring-opening polymerization of many different types of heterocyclic monomers. In particular, epoxide monomers undergo especially rapid polymerization with these catalysts. Investigations have shown that in the case of platinum and rhodium catalysts these polymerizations proceed at the surface of the metal colloids by means of a novel cationic mechanism. In contrast, polymerizations with octacarbonyldicobalt take place by a homogeneous cationic mechanism. In all cases, polymerization appears to proceed by the formal attack of a positively charged silicon species on the heteroatom with the formation of a silicon-oxygen bond. Interesting comb, graft, block and network polymers can be prepared by carrying out simultaneous epoxide ring-opening and hydrosilation reactions using these catalysts.     

Metal-catalyzed radical polyaddition as a novel polymer synthetic route

A new class of polymerizations was developed via metal-catalyzed C-C bond forming radical polyaddition; the monomers were designed to have a reactive C-Cl bond, which can be activated by the metal catalysts to generate a carbon radical species, along with a C=C double bond, to which the carbon radical generated from another molecule adds to form a C-C backbone polymer with an inactive C-Cl pendant.     

Dilute anionic surfactant solution route to polyaniline rectangular sub-microtubes as a novel nanostructure

A facile and low-cost approach has been developed for tailoring polyaniline rectangular sub-microtubes as a novel nanostructure of a conducting polymer in dilute sodium dodecyl sulfate (SDS) solution by the oxidation polymerization of aniline at room temperature. It was found that the size and uniformity of polyaniline rectangular sub-microtubes could be appropriately adjusted by tuning the concentration of aniline and the molar ratio of oxidant to aniline, respectively. The morphological evolution of rectangular sub-microtubes under different reaction times has been followed, and a possible formation mechanism has also been discussed in this report. The directing role of other anionic surfactants with -SO3(-) as the hydrophilic group for constructing polyaniline rectangular sub-microtubes has been investigated in detail.     

Oxidation of Pt-bound bis-hydroxylamine as a novel route to unexplored dinitrosoalkane ligated species

The reaction of K 2[PtCl 4] and HO(H)NCMe 2CMe 2N(H)OH.H 2SO 4 ( BHA.H 2SO 4; 2) in a molar ratio 1:2 at 20-25 degrees C in water affords a mixture of [Pt(BHA) 2][PtCl 4] ( 5) and [Pt(BHA-H) 2] ( 6) ( BHA- H = anionic monodeprotonated form of BHA) which, upon heating at 80-85 degrees C for 12 h or on prolonged keeping at 20-25 degrees C for 2 weeks, is subject to a slow transformation giving [PtCl 2(BHA)] ( 7). The latter compound is also obtained from the reaction between K[PtCl 3(Me 2 SO)] and 2. The chlorination of [PtCl 2(BHA)] ( 7) in freshly distilled dry chloroform leads to the selective oxidation of one N(H)OH group yielding [PtCl 2{HO(H) NCMe 2CMe 2 N=O}] ( 13), while the chlorination in water produces the complex [PtCl 2(O= NCMe 2CMe 2 N=O)] ( 14) bearing the unexplored dinitrosoalkane species. Treatment of 14 with 2 equiv of 1,2-bis-(diphenylphosphino)ethane (dppe) in CH 2Cl 2 results in the liberation of the dinitrosoalkane ligand followed by its fast cyclization giving the alpha-dinitrone (3,3,4,4-tetramethyl-1,2-diazete-1,2-dioxide) in solution and the solid [Pt(dppe) 2](Cl) 2. The Pt (II) complexes with hydroxylamino ( intersection)oximes [PtCl 2{HO(H) NC(Me) 2C(R)= NOH}] (R = Me 8; R = Ph 9) upon their oxidation with Cl 2 in CHCl 3 afford the nitrosoalkane derivatives [PtCl 2{O= NCMe 2C(R)= NOH}] (R = Me 16; Ph 17), respectively, while the corresponding chlorination of the bis-chelates [Pt{HO(H) NCMe 2C(R)= NOH} 2] (R = Me 10; Ph 11) gives [Pt{O= NCMe 2C(R)= NO} 2] (R = Me 18; Ph 19). The formulation of 5- 19 is based on C, H, and N microanalyses, IR, 1D ( (1)H, (13)C{ (1)H}, (195)Pt) and 2D ( (1)H, (1)H-COSY, (1)H, (13)C-HSQC) NMR spectroscopies, and X-ray diffraction for five complexes ( 5, 7, and 12- 14).     

A novel route to meta-aminobenzotrifluoride

Product patterns can be altered in reactions of $\text{m}$-nitrobenzotrichloride [VI] with [AHF]_x·NH₄F complex. Side-chain fluorination predominates under ‘mild’ conditions. In contrast. ‘forcing’ conditions affected unexpected $\text{in}$-$\text{situ}$ fluorination-reduction to give $\text{m}$-aminobenzotrifluoride [V] in high yield [75%] and purity [99.6%]. $\text{in}$-$\text{situ}$ reduction is probably initiated by a combination of iron from the stainless steel autoclave and trace amounts of moisture. The transformation of [VI] to [V] represents another type of $\text{in}$-$\text{situ}$ fluorination-reduction nitroaromatics, e.g. nitrobenzene [VII] to $\text{p}$-fluoroaniline [VIII]. $\text{o}$-Nitrobenzotrichloride [XI] degraded under ‘forcing’ conditions with [AHF]_x·NH₄F.     

Vinylsilyl Grignard reagents as aryne traps. A new route to (arylalkenyl)silanes.

A general method for preparing (arylalkenyl)silanes via nucleophilic capture of arynes with vinyltrimethylsilyl Grignard reagents is described.     

Triphenylbismuth diacylates as novel reagents for fine organic synthesis

Triphenylbismuth diacylates, Ph₃Bi(O₂CR)₂ (R = Me, Et, Ph, CF₃, CH=CH₂), are novel effective reagents for fine organic synthesis. They oxidize primary and secondary alcohols and di-tert-glycols under mild conditions to form the corresponding carbonyl compounds in high yields;O- andN-phenylate alcohols, enols, and amines; andO- ando-C-phenylate phenols.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2043–2047, December, 1993.     

A novel route to pH oscillators

The formaldehyde–sulfite reaction is an acid to alkali clock reaction in batch, which displays complex behaviour in a flow reactor. Current published mechanisms do not account for the behaviour in an open system. In this Letter, we construct a minimal model based on this system and demonstrate that a base-catalysed rate-determining step coupled with an appropriate OH⁻ consuming reaction can result in bistability and oscillations. The model may provide a method for the design of organic-based pH oscillators.     

Rhodium(I)-catalyzed hydroaminomethylation of 2-isopropenylanilines as a novel route to 1,2,3,4-tetrahydroquinolines

A new atom economical approach for the preparation of 1,2,3,4-tetrahydroquinolines can be achieved by means of the intramolecular hydroaminomethylation of 2-isopropenylanilines, mediated by an ionic diamino rhodium catalyst that does not require phosphine--this reaction is highly chemo- and regioselective, and it occurs in good isolated yields.     

Silica dissolution as a route to octaanionic silsesquioxanes

The octaanion, [OSiO_1.5]₈^8? (OA) is a low cost, discrete nano silica particle that can be made directly from high surface area, amorphous silica reacted with Me₄NOH in water alcohol mixtures. It would be ideal if Me₄NOH could be formed in situ from, for example, Me₄NCl and NaOH, as long known in the literature. This process would reduce costs and enable recycling of Me₄NCl produced in the functionalization of OA with chlorosilanes, RMe₂SiCl, to form [RMe₂SiOSiO_1.5]₈ organic/inorganic hybrid nanobuilding blocks. Kinetic studies were conducted to assess base‐promoted dissolution of fumed silica (25 m 2 /g) as a function of concentrations, times, etc., to form the octaanion [OSiO_1.5]₈^8? using Me₄NOH, NaOH and mixtures of NaOH/Me₄NCl. Surprisingly, we find that small amounts of Me₄NCl greatly inhibit the dissolution reaction for reasons that are as yet unknown. Copyright © 2005 John Wiley & Sons, Ltd.     

Carbene-carbene rearrangements as a route to 1,5-dihydropentalene

1,5-Dihydropentalene (4) is formed as the main product on treatment of trans-1,2-bis(2,2-dibromocyclo-propyl)ethene 3 with methyllithium at −40°. In addition the reaction affords 1- and 2-propadienylcyclopentadienes (5a) and (5b), and trans-1,2,4,6,7-octapentaene (6), new C₈H₈ isomers. Diels-Alder adducts of 4, 5a and 5b were obt in the reaction with perfluorobut-2-yne. The formation of 1,5-dihydropentalene 4 is explained by a double ring expansion sequence involving consecutive carbene-carbene rearrangements with 1,3-carbon and subsequent 1,2-hydrogen shifts, supported by the reaction of double labelled (¹³C-depleted) 3. From readily available 3 at low temperatures formation and fusion of two 5-membered rings are achieved in one step.     

Ruthenium-catalyzed cycloisomerization-6pi-cyclization: a novel route to pyridines

[reaction: see text] Herein we report a method for the synthesis of substituted pyridines. The unsaturated ketones and aldehydes derived from the cycloisomerization of primary and secondary propargyl diynols in the presence of [CpRu(CH3CN)3]PF6 (1) are converted to 1-azatrienes which in turn undergo a subsequent electrocyclization-dehydration to provide pyridines with excellent regiocontrol.     

Group-selective hydroalumination: a novel route to stereogenic tert-alcohol centers

[reaction: see text]. A new group-selective reaction is described, that is, the hydroalumination of bis-alkynyl alcohols armed with an adjacent stereogenic center, giving stereo-defined tert-alcohols of potential utility in natural product synthesis.