Organic thin-film transistors based on carbonyl-functionalized quaterthiophenes: high mobility N-channel semiconductors and ambipolar transport

New carbonyl-functionalized quaterthiophenes, 5, 5' '-diheptanoyl-2,2':5',2' ':5' ',2' '-quaterthiophene (DHCO-4T), 5, 5' '-diperfluorohexylcarbonyl-2,2':5',2' ':5' ',2' '-quaterthiophene (DFHCO-4T), and 2,7-[bis-(5-perfluorohexylcarbonylthien-2-yl)]-4H-cyclopenta[2,1-b:3,4-b']-dithiophen-4-one (DFHCO-4TCO) have been synthesized and characterized. Field-effect transistors fabricated with these materials exhibit high electron mobilities both in a vacuum (up to 0.6 cm2 V-1 s-1) and in air (up to 0.02 cm2 V-1 s-1) and very high Ion:Ioff currents ratios (>107). DHCO-4T is the first organic material exhibiting excellent ambipolar transport (mue/muh up to 0.1/0.01 cm2 V-1 s-1, (Ion:Ioff)e/(Ion:Ioff)h up to 107/108 for the same device) over a broad range of deposition temperatures. These materials are therefore promising for organic complementary circuits.     

L-Proline/CoCl2-catalyzed highly diastereo- and enantioselective direct aldol reactions

The CoCl(2)/L-proline (1:2) system was found to be an excellent catalyst for direct aldol reactions. Excellent yields (up to 93%) and a significant improvement in diastereoselectivity (anti/syn up to 45:1) as well as enantioselectivity (up to more than 99% ee) compared with using proline as the sole catalyst were observed. This catalyst system was successfully applied to both cyclic and acyclic ketones in combination with aromatic and aliphatic aldehydes. In situ chelation of CoCl(2) and proline (1:2) is proposed to promote the reaction through a six-membered Zimmermann-Traxler type transition state involving the positioning of proline-enamine and the aldehyde through chelation to Co(II).     

Copper(II)-catalyzed asymmetric henry reaction of o-alkynylbenzaldehydes followed by gold(I)-mediated cycloisomerization: an enantioselective route to chiral 1H-isochromenes and 1,3-dihydroisobenzofurans

By combining the copper(II)-catalyzed asymmetric Henry reaction of o-alkynylbenzaldehydes with subsequent gold(I)-catalyzed cycloisomerization, optically active 1H-isochromenes and 1,3-dihydroisobenzofurans were successfully synthesized in good overall yields with good to excellent enantioselectivities (up to 98%). Various substrates were investigated, and a correlation between the regioselectivity and electronic nature of the substrates was studied. The substrates with electro-donating groups at the alkynyl moiety preferred a 6-endo-dig manner to generated 1H-isochromenes 3 as main products (up to >30:1) while the ones with electron-withdrawing groups were inclined to undergo 5-exo-dig cyclization to form 1,3-dihydroisobenzofurans 4 (up to 1:5).     

O(1D)+Si(CH3)3Cl反应生成振动激发的OH(ν≤3)

The vibrationally excited OH(v) from the reaction of O(~1D)+Si(CH_3)_3Cl was observed by UV laser photolysis/FTIR emission spectroscopy. The vibrational number was only up to 3 with a ratio of 1:0.8:0.1 for v=1:2:3. Comparing this result with the similar reaction of O(~1D)+Si(CH_3)_4 which OH(v) vibrational number was high up to 4 with a ratio of 1:1:1:0.3 for v=1:2:3:4 under the same experimental conditions, it was found that the substitution of Cl for CH_3 affected the extent of heavy Si atom blocking the energy migration in a molecule. This results identifies the prediction that the characteristic of electrons in central atom plays an important role in intramolecular energy transfer.     

DNA sequencing by capillary electrophoresis using copolymers of acrylamide and N,N-dimethylacrylamide

Copolymers of acrylamide (AM) and N,N-dimethylacrylamide (DMA) with AM to DMA molar ratios of 3:1, 2:1 and 1:1 and molecular weights of about 2.2 MDa were synthesized. The polymers were tested as separation media in DNA sequencing analysis by capillary electrophoresis (CE). The dynamic coating ability of polydimethylacrylamide (PDMA) and the hydrophilicity of polyacrylamide (PAM) have been successfully combined in these random copolymers. A separation efficiency of over 10 million theoretical plates per meter has been reached by using the bare capillaries without the additional polymer coating step. Under optimized separation conditions for longer read length DNA sequencing, the separation ability of the copolymers decreased with decreasing AM to DMA molar ratio from 3:1, 2:1 and 1:1. In comparison with PAM, the copolymer with a 3:1 AM:DMA ratio showed a higher separation efficiency. By using a 2.5% w/v copolymer with 3:1 AM:DMA ratio, one base resolution of 0.55 up to 699 bases and 0.30 up to 963 bases have been achieved in about 80 min at ambient temperatures.     

Asymmetric synthesis of 2,6-substituted dihydropyrone catalyzed by 3-monosubstituted and 3,3′-bisubstituted BINOL titanium complexes

Asymmetric hetero-Diels-Alder (HDA) reactions of aromatic aldehydes with Danishefsky’s diene derivative were carried out smoothly in the presence of the Ti(IV)-(R)-BINOL (1:1.2) complex to give the corresponding chiral 2,6-disubstituted dihydropyrones under mild conditions. The readily accessible I-Ti(OCH(CH₃)₂)₄ (1.2:1) complex was found to be an effective catalyst for this reaction. Aromatic aldehydes afforded the corresponding products in moderate yields (up to 72 %) with good enantioselectivities (up to 80 % ee). Aromatic aldehydes in presence of the TiCl₄-NaOCH₃-II (1:4.2:1.2) complex gave the products in higher yields (up to 73 %) with better enantioseletivities (up to 84 % ee).     

Asymmetric Michael addition catalysed by sugar-based prolinamides in solvent-free conditions

Sugar-based prolinamides derived from glucosamine have been developed as organocatalysts for the asymmetric Michael addition between cyclohexanones and nitroolefins. Numerous polar and nonpolar solvents and additives have been screened in the current study. The organocatalyst 1c in the presence of benzoic acid as additive catalysed the reaction under neat conditions to afford Michael adducts in high yields (up to 98%) with excellent diastereoselectivities (up to >99:1) and moderate enantiomeric ratios (up to 84:16).     

A convenient route to enantiopure 3-aryl-2,3-diaminopropanoic acids by diastereoselective Mannich reaction of camphor-based tricyclic iminolactone with imines

A novel and convenient route to the asymmetric synthesis of 2,3-diamino acids via Mannich reaction of iminolactones 1a and 1b with N-protected imines has been achieved in good yields (up to 95%) and high diastereoselectivity (dr: >99:1). Hydrolysis of the Mannich adducts under acidic conditions furnished the desired 3-aryl-2,3-diaminopropanoic acids in good yields (up to 85%) with excellent enantiomeric excesses (99% ee).     

Diastereoselective reactions of delta-oxy-substituted allylic acetates with organocopper reagents

S(N)2' (gamma) substitutions of delta-substituted allylic acetates with Grignard reagents and copper catalysts proceed with high diastereoselectivities. With benzyloxy, methoxymethoxy, and tert-butyldimethylsiloxy groups, reactions favor the anti-isomer with selectivities up to anti:syn = >99:1. With a hydroxyl group, selectivities are reversed and the syn-isomer is favored with selectivities up to anti:syn = <1:99.     

Metalloporphyrin-mediated asymmetric nitrogen-atom transfer to hydrocarbons: aziridination of alkenes and amidation of saturated C-H bonds catalyzed by chiral ruthenium and manganese porphyrins

Chiral metalloporphyrins [Mn(Por*)(OH)(MeOH)] (1) and [Ru(Por*)(CO)(EtOH)] (2) catalyze asymmetric aziridination of aromatic alkenes and asymmetric amidation of benzylic hydrocarbons to give moderate enantiomeric excesses. The mass balance in these nitrogen-atom-transfer processes has been examined. With PhI=NTs as the nitrogen source, the aziridination of styrenes, trans-stilbene, 2-vinylnaphthalene, indene, and 2,2-dimethylchromene catalyzed by complex 1 or 2 resulted in up to 99 % substrate conversions and up to 94 % aziridine selectivities, whereas the amidation of ethylbenzenes, indan, tetralin, 1-, and 2-ethylnaphthalene catalyzed by complex 2 led to substrate conversions of up to 32 % and amide selectivities of up to 91 %. Complex 1 or 2 can also catalyze the asymmetric amidation of 4-methoxyethylbenzene, tetralin, and 2-ethylnaphthalene with "PhI(OAc)(2) + NH(2)SO(2)Me", affording the N-substituted methanesulfonamides in up to 56 % ee with substrate conversions of up to 34 % and amide selectivities of up to 92 %. Extension of the "complex 1 + PhI=NTs" or "complex 1 + PhI(OAc)(2) + NH(2)R (R=Ts, Ns)" amidation protocol to a steroid resulted in diastereoselective amidation of cholesteryl acetate at the allylic C-H bonds at C-7 with substrate conversions of up to 49 % and amide selectivities of up to 90 % (alpha:beta ratio: up to 4.2:1). An aziridination- and amidation-active chiral bis(tosylimido)ruthenium(VI) porphyrin, [Ru(Por*)(NTs)(2)] (3), and a ruthenium porphyrin aziridine adduct, [Ru(Por*)(CO)(TsAz)] (4, TsAz=N-tosyl-2- (4-chlorophenyl)aziridine), have been isolated from the reaction of 2 with PhI=NTs and N-tosyl-2-(4-chlorophenyl)aziridine, respectively. The imidoruthenium porphyrin 3 could be an active species in the aziridination or amidation catalyzed by complex 2 described above. The second-order rate constants for the reactions of 3 with styrenes, 2-vinylnaphthalene, indene, ethylbenzenes, and 2-ethylnaphthalene range from 3.7-42.5x10(-3) dm(3) mol(-1) s(-1). An X-ray structure determination of complex 4 reveals an O- rather than N-coordination of the aziridine axial ligand. The fact that the N-tosylaziridine in 4 does not adopt an N-coordination mode disfavors a concerted pathway in the aziridination by a tosylimido ruthenium porphyrin active species.     

Highly efficient and reusable dendritic catalysts derived from N-prolylsulfonamide for the asymmetric direct aldol reaction in water

The direct aldol reactions catalyzed by chiral dendritic catalysts derived from N-prolylsulfonamide gave the corresponding products in high isolated yields (up to 99%) with excellent anti diastereoselectivities (up to >99:1) and enantioselectivities (up to >99% ee) in water. In addition, catalyst 1e may be recovered by precipitation and filtration and reused for at least five times without loss of catalytic activity.     

Rationally designed organocatalyst for direct asymmetric aldol reaction in the presence of water

A rationally designed organocatalyst for direct asymmetric aldol reaction in the presence of water has been developed. High yield (up to 99%), diastereoselectivity (up to 99:1) and enantioselectivity (up to 97%) were obtained under optimal conditions.     

Readily tunable and bifunctional L-prolinamide derivatives: design and application in the direct enantioselective Aldol reactions

[reaction: see text] Readily tunable and bifunctional L-prolinamides as novel organocatalysts have been developed, and their catalytic activities were evaluated in the direct asymmetric Aldol reactions of various aromatic aldehydes and cyclohexanone. High isolated yields (up to 94%), enantioselectivities (up to 99% ee), and anti-diastereoselectivities (up to 99:1) were obtained under the optimal conditions.     

Diastereo- and enantioselective synthesis of oxazine and oxazolidine derivatives with a chiral quaternary carbon center under multifunctional catalysis

An easy one-pot, multistep cascade reaction which could afford a series of substituted benzo[d]pyrido[2,1-b]oxazolidine and [1,3]oxazine derivatives in a highly enantio- (up to 98% ee) and diastereoselective (4:1 to >20:1 dr) manner with generally good to excellent yields (up to 99%) has been developed. This well designed strategy could be applied to a wide scope of substrates under mild conditions with simple operations.     

Catalysis of 3-pyrrolidinecarboxylic acid and related pyrrolidine derivatives in enantioselective anti-Mannich-type reactions: importance of the 3-acid group on pyrrolidine for stereocontrol

The development of enantioselective anti-selective Mannich-type reactions of aldehydes and ketones with imines catalyzed by 3-pyrrolidinecarboxylic acid and related pyrrolidine derivatives is reported in detail. Both (3R,5R)-5-methyl-3-pyrrolidinecarboxylic acid and (R)-3-pyrrolidinecarboxylic acid efficiently catalyzed the reactions of aldehydes with alpha-imino esters under mild conditions and afforded anti-Mannich products with high diastereo- and enantioselectivities (anti/syn up to 99:1, up to >99% ee). For the reactions of ketones with alpha-imino esters, (R)-3-pyrrolidinecarboxylic acid was an efficient catalyst (anti/syn up to >99:1, up to 99% ee). Evaluation of a series of pyrrolidine-based catalysts indicated that the acid group at the beta-position of the pyrrolidine ring of the catalyst played an important role in forwarding the carbon-carbon bond formation and in directing anti-selectivity and enantioselectivity.     

Pyrrolidine-thioxotetrahydropyrimidinone as an efficient organocatalyst for the enantioselective Michael addition of cyclic ketones to nitrodienes

Among the various Michael additions, the enantioselective reaction between cyclic ketones and nitrodienes has received little attention in comparison to the corresponding reaction with nitroolefins. A bifunctional organocatalyst consisting of the pyrrolidine moiety and a thioxotetrahydropyrimidinone ring successfully catalyzed this asymmetric transformation. The products of the reaction between various ketones and nitrodienes were obtained in high yields (up to 96%) with excellent diastereo- (up to >98:2 dr) and enantioselectivities (up to 99:1% er).     

Highly enantioselective hetero Diels–Alder reactions of N-sulfinyl dienophiles promoted by copper(II)- and zinc(II)-chiral bis(oxazoline) complexes

Hetero Diels–Alder reactions of 1,3-cyclohexadiene with N-sulfinyl dienophiles 1a or 1b, promoted by Cu(II)- or Zn(II)-chiral bis(oxazoline) complexes, afforded endo adducts in high yields (up to 85%) and enantiomeric excess (e.e. of up to >98%) under stoichiometric conditions. With 10 mol% loading of the Zn(II) catalyst up to 75% e.e. was obtained for the endo adduct (endo:exo=10:1, total yield 68%).     

Highly diastereoselective epoxidation of allyl-substituted cycloalkenes catalyzed by metalloporphyrins

Highly diastereoselective epoxidations of allyl-substituted cycloalkenes including allylic alcohols, esters, and amines using sterically bulky metalloporphyrins [Mn(TDCPP)Cl] (1) and [Ru(TDCPP)CO] (2) as catalysts have been achieved. The "1 + H(2)O(2)" and "2 + 2,6-Cl(2)pyNO" protocols afforded trans-epoxides selectively in good yields (up to 99%) with up to >99:1 trans-selectivity.     

syn-selective direct catalytic asymmetric Mannich-type reactions of hydroxyketones using Y{N(SiMe3)2}3/linked-BINOL complexes

[reaction, structure: see text] Chiral Y{N(SiMe3)2}3/linked-BINOL catalyst generated Y-enolate in situ from various hydroxyketones (R2 = aryl, heteroaryl). Beta-amino-alpha-hydroxy ketones (R1 = aryl, heteroaryl, alkenyl) were obtained syn-selectively (up to 96/4) in high ee (up to 98%) and good yield (up to 98% yield).     

Synthesis of Chiral 2‐Aroyl‐1‐tetralols: Asymmetric Transfer Hydrgenation of 2‐Aroyl‐1‐tetralones via Dynamic Kinetic Resolution

The dynamic kinetic resolution of 2‐aroyl‐1‐tetralones was achieved via asymmetric transfer hydrogenation using (S,S)‐RuCl(p‐cymene)TsDPEN (TsDPEN=N‐(tosyl)‐1,2‐diphenylethylenediamine) in formic acid/triethyl‐ amine (5:2, molar ratio), afforded the desired products in good yields (up to 85%) with diastereomeric ratio up to >99:1 and high enantiomeric excesses (up to >99%). The absolute configuration of major the product was confirmed by X‐ray crystal structure analysis.