Glacial retreat on the Tibetan Plateau and surrounding regions is characteristic since 1960s has intensified in past 10 yr. The magnitude of glacial relatively small interior increases to margins plateau, with greatest around edges. this region impacting hydrological processes regions. caused an increase more than 5.5% river runoff from plateau. In some areas, such as Tarim River basin, greater. also rising lake levels areas large coverage glaciers, Nam Co Lake Selin areas. Rising are...

Spiral bound: The Morita–Baylis–Hillman adducts were employed as C3 synthons in the asymmetric [3+2] annulation with malonitrile substrates using L-threonine-derived 1 catalyst (see scheme). reaction is highly regioselective and stereoselective, affords optically enriched 3-spirocyclopentene-2-oxindoles containing two contiguous quaternary centers. Boc=tert-butoxycarbonyl, PMB=para-methoxybenzyl, TIPS=triisopropylsilyl. Detailed facts of importance to specialist readers are published...

Active ingredient: Optically active tetrahydroquinolines and tetrahydroisoquinolines can be obtained by the asymmetric hydrogenation of quinolines isoquinolines with chloroformates as activating reagent (e.g., ClCO2Bn, see scheme). The method has been applied to synthesis several naturally occurring alkaloids. Bn=benzyl. Supporting information for this article is available on WWW under http://www.wiley-vch.de/contents/jc_2002/2006/z503073_s.pdf or from author. Please note: publisher not...

A new family of dipeptide-based chiral phosphines was designed and prepared. d-Thr-l-tert-Leu-derived catalyst 4c promoted [3 + 2] cycloaddition allenoates to α-substituted acrylates in a regiospecific stereoselective manner, furnishing functionalized cyclopentenes with quaternary stereogenic centers high yields excellent enantioselectivities.

A fast one: The title reaction proceeds in the presence of 5 mol % catalyst 1, and is complete within an hour. 2-alkyl- 2-aryl-substituted 3-pyrroline products are obtained good yield with high enantioselectivity. application method to concise formal synthesis (+)-trachelanthamidine also demonstrated. Boc=tert-butoxycarbonyl, M.S.=molecular sieves, TBDPS=tert-butyldiphenylsilyl. Detailed facts importance specialist readers published as "Supporting Information". Such documents peer-reviewed,...

Highly enantioselective [4 + 2] annulation of activated alkenes with α-substituted allenoates catalyzed by amino acid-based bifunctional phosphines has been developed for the first time, which provides an easy access to optically enriched functionalized cyclohexenes. In particular, 3-spirocyclohexene-2-oxindoles were prepared in high yields and excellent enantioselectivities.

Using Pd(CF3CO2)2/(S,S)-f-binaphane as the catalyst, an efficient enantioselective synthesis of cyclic sulfamidates was developed via asymmetric hydrogenation corresponding imines in 2,2,2-trifluoroethanol at room temperature with high enantioselectivities (up to 99% ee).

Pd/bisphosphines complexes are highly effective catalysts for asymmetric hydrogenation of activated imines in trifluoroethanol. The N-diphenylphosphinyl ketimines 3 with Pd(CF3CO2)/(S)-SegPhos indicated 87-99% ee, and N-tosylimines 5 could gave 88-97% ee Pd(CF3CO2)/(S)-SynPhos as a catalyst. Cyclic N-sulfonylimines 7 11 were hydrogenated to afford the useful chiral sultam derivatives 79-93% which important organic synthetic intermediates structural units agricultural pharmaceutical agents.

A series of novel bifunctional phosphine−sulfonamide organic catalysts were designed and readily prepared from natural amino acids, they utilized to promote enantioselective aza-Morita−Baylis−Hillman (MBH) reactions. l-Threonine-derived 9b was found be the most efficient catalyst, affording desired aza-MBH adducts in high yields with excellent enantioselectivities.

Aktiver Bestandteil: Optisch aktive Tetrahydrochinoline und Tetrahydroisochinoline lassen sich durch asymmetrische Hydrierung von Chinolinen bzw. Isochinolinen mit Chlorformiaten wie ClCO2Bn als aktivierenden Reagentien herstellen (siehe Schema). Auf diese Art gelang die Synthese vieler natürlicher Alkaloide. Bn=Benzyl.

As a significant complement to amino catalysts, phosphines are versatile Lewis base catalysts capable of promoting wide range diverse organic transformations. In particular, chiral bearing Brønsted acid moiety have recently emerged as powerful bifunctional phosphine in asymmetric synthesis and catalysis. this account, we document our recent efforts on the design development novel acid/dipeptide-based phosphines, their applications enantio­selective (aza)-Morita-Baylis-Hillman (MBH) reactions...

A series of bifunctional phosphine–thiourea organic catalysts based on natural amino acid scaffolds were designed and prepared. L-Threonine-derived phosphine found to be very efficient in promoting asymmetric Morita–Baylis–Hillman (MBH) reaction acrylates with aromatic aldehydes, affording the desired MBH adducts up 90% ee. To gain mechanistic insights into reaction, effects adding various additives investigated. We propose that hydrogen bonding interactions between thiourea moiety catalyst...

Background: A learning-type artificial pancreas has been proposed to exploit the repetitive nature in blood glucose dynamics. We clinically evaluated efficacy of pancreas. Methods: conducted a pilot clinical study 10 participants mean age 36.1 years (standard deviation [SD] 12.7; range 16–58) with type 1 diabetes. Each trial was for eight consecutive mornings. The first two mornings were open-loop obtain individualized parameters. Then, following six closed-loop, during which model...

Abstract Backgrounds: Cancer is one of the main causes death worldwide, seriously threatening human health and life expectancy. We aimed to analyze cancer incidence mortality rates during 2016 in Zhejiang Province, Southeast China. Methods: Data were collected from 14 population-based registries across Province stratified by sex region analyzed. The crude rate, age-standardized age-specific region-specific cumulative rate calculated. proportions 10 common cancers different groups top five...

We address a distributed adaptive control methodology for nonlinear interconnected systems possibly affected by network anomalies. In the framework of approximation, controller and parameter estimator are designed exploiting backstepping approach. The stability system under anomalies is analyzed, where both local neighboring anomaly effects considered. To quantify resilience action anomalies, we derive bounds on duration each resting time between two consecutive Specifically, when smaller...

[reaction: see text]. A novel catalytic system for asymmetric hydrogenation of functionalized ketones has been developed using a Pd/bisphosphine complex as the catalyst in 2,2,2-trifluoroethanol. The reaction exhibits high enantioselectivity, and up to 92.2% ee was obtained.

Asymmetric alkynylation of seven-membered cyclic imine dibenzo[b,f][1,4]oxazepines is successfully achieved by combining chiral phosphoric acid and Ag(I) catalysts. Various arylacetylenes, conjugated enynes, terminal 1,3-diynes are good substrates for this reaction, aliphatic hexyne also a suitable donor at elevated temperature. Optimization approach has provided facile method to synthesize optically active 11-substituted-10,11-dihydrodibenzo[b,f][1,4]oxazepine derivatives containing...

A specific regioselective direct Mannich reaction of methyl alkyl ketones with cyclic imines benzo[<italic>e</italic>][1,2,3]oxathiazine 2,2-dioxides is realized 87–97% ee.

A method for fault detection (FD) of networked control systems with unknown network-induced delay and input based on eigendecomposition, adaptive evaluation threshold is proposed in this paper. In the method, a known structure matrix which supposed to be smaller than one sampling period extracted by eigendecomposition an observer residual generator constructed. Then function ensure optimal robustness at stage Parity Space approach. Finally, estimation maximal influence random function,...

Abstract By using a phosphane as an organocatalyst, efficient synthesis of benzo‐fused cyclic sulfamidate heterocycles has been developed through cycloaddition reaction allenoate and imines including trifluoromethyl ketimine, which gave high yields (71–97 %). The could also be conveniently performed on gram scale. Furthermore, some simple transformations the heterocycle products have disclosed to obtain functional amines. An asymmetric variant this was tried by screening several commercially...

Abstract An enantioselective direct Mannich reaction of different acetophenone derivatives with various substituted seven‐membered cyclic imines using ( S )‐azetidine‐2‐carboxylic acid as an organocatalyst is described, which provides efficient access to optically active 11‐substituted‐10,11‐dihydrodibenzo[ b , f ][1,4]oxazepine 87–95 % ee . For α,β‐unsaturated ketone benzalacetone, the desired product was obtained 72 A plausible transition state established explain observed absolute...

Abstract 3‐Substituted‐2 H ‐1,4‐benzoxazines undergo a highly enantioselective direct Mannich reaction with acetone in the presence of an L ‐proline catalyst at room temperature. The corresponding N‐heterocycles α‐tetrasubstituted carbon stereocenters were obtained good yields (48–92%) and excellent enantioselectivity (up to &gt;99% ee ). Furthermore, novel modification involving diastereoselective reduction adduct was carried out leading formation 1,3‐amino alcohol chiral tetrasubstituted...