scholarly journals General and stereoselective aminoxylation of biradical titanium(iv) enolates with TEMPO: a detailed study on the effect of the chiral auxiliary

2018 ◽  
Vol 16 (26) ◽  
pp. 4807-4815
Author(s):  
Stuart C. D. Kennington ◽  
Alejandro Gómez-Palomino ◽  
Ernest Salomó ◽  
Pedro Romea ◽  
Fèlix Urpí ◽  
...  
Keyword(s):  
Chiral Auxiliary ◽  
Single Diastereomer ◽  
High Yields

Reactions of Ti(iv) enolates from N-acyl-4-tert-butyl-1,3-oxazolidine-2-thiones with TEMPO afford a single diastereomer of aminoxylated adducts in high yields.

An Efficient Method for Constructing Cyclic β-Amino Acids Bearing Quaternary Stereocenters

Synlett ◽  
2019 ◽  
Vol 30 (05) ◽  
pp. 593-599 ◽  
Author(s):  
Shende Jiang ◽  
Guang Yang ◽  
Shuanglin Qin ◽  
Tongtong Liu ◽  
Yunhao Luo ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Efficient Method ◽  
Ester Group ◽  
Chiral Auxiliary ◽  
Allyl Ester ◽  
Stereogenic Centers ◽  
Quaternary Stereocenters ◽  
High Yields ◽  
Quaternary Stereogenic Centers

This paper describes an efficient method for constructing cyclic β-amino acids bearing quaternary stereocenters. NaHMDS-promoted asymmetric α-alkylation was employed to obtain the key intermediates with quaternary stereogenic centers, which were subsequently reduced by NaBH4 in 10% methanol in THF, with high yields and high diastereoselectivities. By removing the allyl ester group and the chiral auxiliary, the corresponding cyclic β-amino acid hydrochlorides were finally obtained.

Novel enantioselective synthesis of (S)-ketamine using chiral auxiliary and precursor Mannich base

2019 ◽  
Vol 97 (5) ◽  
pp. 331-336 ◽  
Author(s):  
Seyed Jamaladdin Gohari ◽  
Abdollah Javidan ◽  
Abolghasem Moghimi ◽  
Mohammad Javad Taghizadeh ◽  
Maryam Iman
Keyword(s):  
Acid Solution ◽  
Nucleophilic Addition ◽  
Grignard Reagent ◽  
Mannich Base ◽  
Enantioselective Synthesis ◽  
Chiral Auxiliary ◽  
Chiral Auxiliaries ◽  
Anesthetic Drug ◽  
Directing Group ◽  
High Yields

Ketamine has been extensively used as an anesthetic drug. Chiral auxiliaries such as tert-butanesulfinamide (TBSA) can be used for the asymmetric synthesis of (S)-ketamine. Condensation of TBSA with ketones provides tert-butanesulfinylimines in consistently high yields. The tert-butanesulfinyl group actuates the imine for nucleophilic addition, is a potent chiral directing group, and after nucleophilic addition is easily dissociated by intervention with acid solution. To prepare 2-(N-piperidinomethyl)-1-phenylcyclohexylamine (1), we started with the cyclohexanone and using Mannich reaction achieved an aminoketone. Then, we made the sulfiniylamin (2) by the condensation of TBSA with aminoketone. By using salts such as Ti(OEt)4, we obtained N-tert-butanesulfinylketimine in 85% yield. Next, we provided a new chiral center (3) using Grignard reagent as nucleophile at −78 °C (80% yield). Finally, after many steps, the (S)-ketamine synthesized under ozonolysis conditions, with good yield and enantioselectivity (75% yield and 75% ee).

A Simple Method for Preparing Fibrinogen

1966 ◽  
Vol 16 (01/02) ◽  
pp. 198-206 ◽  
Author(s):  
W Straughn ◽  
R. H Wagner
Keyword(s):  
Barium Sulfate ◽  
Caproic Acid ◽  
Aminobutyric Acid ◽  
Gamma Aminobutyric Acid ◽  
Human Fibrinogen ◽  
Simple Method ◽  
High Yields ◽  
Marked Stability

SummaryA simple new procedure is reported for the isolation of canine, bovine, porcine, and human fibrinogen. Two molar β-alanine is used to precipitate fibrinogen from barium sulfate adsorbed plasma. The procedure is characterized by dependability and high yields. The material is 95% to 98% clottable protein but still contains impurities such as plasminogen and fibrin-stabilizing factor. Plasminogen may be removed by adsorption with charcoal. The fibrinogen preparations exhibit marked stability to freezing, lyophilization, and dialysis. Epsilon-amino-n-caproic acid and gamma-aminobutyric acid which were also studied have the property of precipitating proteins from plasma but lack the specificity for fibrinogen found with β-alanine.

A Novel Method for the Rapid Purification of Human and Rat Fibrin(OGEN) Degradation Products in High Yields

1979 ◽  
Author(s):  
W. Nieuwenhuizen ◽  
I. A. M. van Ruijven-Vermeer ◽  
F. Haverkate ◽  
G. Timan
Keyword(s):  
Degradation Products ◽  
Complete Separation ◽  
Purification Method ◽  
Amino Terminal ◽  
Novel Method ◽  
Rapid Purification ◽  
The One ◽  
High Yields ◽  
Size Heterogeneity ◽  
D Dimer

A novel method will be described for the preparation and purification of fibrin(ogen) degradation products in high yields. The high yields are due to two factors. on the one hand an improved preparation method in which the size heterogeneity of the degradation products D is strongly reduced by plasmin digestion at well-controlled calcium concentrations. At calcium concentrations of 2mM exclusively D fragments, M.W.= 93-000 (Dcate) were formed; in the presence of 1OmM EGTA only fragments M.W.= 80.000 (D EGTA) were formed as described. on the other hand a new purification method, which includes Sephadex G-200 filtration to purify the D:E complexes and separation of the D and E fragments by a 16 hrs. preparative isoelectric focussing. The latter step gives a complete separation of D (fragments) (pH = 6.5) and E fragments (at pH = 4.5) without any overlap, thus allowing a nearly 100% recovery in this step. The overall recoveries are around 75% of the theoretical values. These recoveries are superior to those of existing procedures. Moreover the conditions of this purification procedure are very mild and probably do not affect the native configuration of the products. Amino-terminal amino acids of human Dcate, D EGTA and D-dimer are identical i.e. val, asx and ser. in the ratgly, asx and ser were found. E 1% for rat Dcate=17-8 for rat D EGTA=16.2 and for rat D- dimer=l8.3. for the corresponding human fragments, these values were all 20.0 ± 0.2.

Studi Awal Geologi di Daerah Beruang Kanan Kabupaten Gunung Mas Propinsi Kalimantan Tengah

PROMINE ◽  
2018 ◽  
Vol 6 (1) ◽  
pp. 1-11
Author(s):  
Retno Anjarwati ◽  
Arifudin Idrus ◽  
Lucas Donny Setijadji
Keyword(s):  
Gold Mineralization ◽  
Volcanic Rocks ◽  
Gold Deposits ◽  
Central Kalimantan ◽  
Magmatic Arc ◽  
Tertiary Sediment ◽  
Copper Gold ◽  
Regional Tectonic ◽  
Mineralization Processes ◽  
High Yields

The regional tectonic conditions of the KSK Contract of Work are located in the mid-Tertiary magmatic arc (Carlile and Mitchell, 1994) which host a number of epithermal gold deposits (eg, Kelian, Indon, Muro) and significant prospects such as Muyup, Masupa Ria, Gunung Mas and Mirah. Copper-gold mineralization in the KSK Contract of Work is associated with a number of intrusions that have occupied the shallow-scale crust at the Mesozoic metamorphic intercellular junction to the south and continuously into the Lower Tertiary sediment toward the water. This intrusion is interpreted to be part of the Oligocene arc of Central Kalimantan (in Carlile and Mitchell 1994) Volcanic rocks and associated volcanoes are older than intrusions, possibly aged Cretaceous and exposed together with all three contacts (Carlile and Mitchell, 1994) some researchers contribute details about the geological and mineralogical background, and some papers for that are published for the Beruang Kanan region and beyond but no one can confirm the genesis type of the Beruang Kanan region The mineralization of the Beruang Kanan area is generally composed by high yields of epithermal sulphide mineralization. with Cu-Au mineralization This high epithermal sulphide deposition coats the upper part of the Cu-Au porphyry precipitate associated with mineralization processes that are generally controlled by the structure

Evaluation of germ plasm for resistant to Soybean mosaic virus (SMV)

2020 ◽  
Vol 21 (1) ◽  
pp. 6-9
Author(s):  
Wuye Ria Andayanie
Keyword(s):  
Abiotic Stress ◽  
Environmental Factors ◽  
Mosaic Virus ◽  
Polyclonal Antibody ◽  
Symptom Severity ◽  
Germ Plasm ◽  
Polyclonal Antibodies ◽  
Soybean Mosaic Virus ◽  
High Yield ◽  
High Yields

Soybean superior varieties with high yields and are resistant to abiotic stress have been largely released, although some varieties grown in the field are not resistant to SMV. In addition, the opportunity to obtain lines of hope as prospective varieties with high yield and resistance to SMV is very small. The method for evaluating soybean germplasm is based on serological observations of 98 accessions of leaf samples from SMV inoculation with T isolate. The evaluation results of 98 accessions based on visual observations showed 31 genotypes reacting very resistant or healthy to mild resistant category to SMV T isolate  with a percentage of symptom severity of 0 −30 %. Among 31 genotypes there are 2 genotypes (PI 200485; M8Grb 44; Mlg 3288) with the category of visually very resistant and resistant, respectively and  Mlg 3288  with the category of mild resistant.  They have a good agronomic appearance with a weight of 100 seeds (˃10 g) and react negatively with polyclonal antibodies to SMV, except Mlg 3288 reaction is not consistent, despite the weight of 100 seeds (˃ 10 g). Leaf samples from 98 accessions revealed various symptoms of SMV infection in the field. This diversity of symptoms is caused by susceptibility to accession, when infection occurs, and environmental factors. Keywords—: soybean; genotipe; Soybean mosaic virus (SMV); disease severity; polyclonal  antibody

Varieties of sweet potato and features of their cultivation technology

2020 ◽  
pp. 18-20
Author(s):  
Т.Э. Остонакулов ◽  
А.А. Шамсиев
Keyword(s):  
Sweet Potato ◽  
Sweet Potatoes ◽  
Marketable Yield ◽  
Early Maturity ◽  
Potato Varieties ◽  
Cultivation Technology ◽  
High Yields ◽  
Sprout Formation ◽  
Yield Formation

В 2017–2019 годах изучены сортообразцы сладкого картофеля на староорошаемых лугово-сероземных почвах Зарафшанской долины. Цель исследований – комплексная оценка сортообразцов батата в условиях Зарафшанской долины по скороспелости, росту, развитию, интенсивному размножению, формированию урожая, компактности клубней в гнезде, продуктивности, урожайности и лежкости клубней и выделение из них перспективных, а также разработка приемов агротехнологии получения высоких урожаев для данных условий. Почвы опытного участка характеризуются благоприятными агрофизическими и водными свойствами и низким содержанием гумуса, нитратного азота, подвижного фосфора и содержанием обменного калия от низкого до среднего. Сравнивали 18 сортообразцов батата. Выделенные сортообразцы изучали при ширине междурядий 70 и 90 см со схемой 70×25 и 90×20 см по 1, 2 и 3 растения в гнезде. Для получения рассады сортообразцов батата брали по 40 клубней и высаживали 20–22 февраля в пленочной теплице при температуре 15–18 °C, заделывая их на глубину 3–5 см. Влажность почвы поддерживали на уровне 65–70%. Через 7–10 дней после высадки почки начинают прорастать, а через 43–48 дней формируется рассада высотой 12–15 см, готовая для высадки в поле. Высадка рассады, как и других рассадных культур (томата, перца, баклажана) – по схеме 70×20–25 см во второй-третьей декаде апреля. Уход включал в себя междурядную обработку (культивация), прополку, борьбу с сорняками, подкормку, поливы. Уборка урожая – в конце сентября-начале октября с помощью картофелекопателя. В результате исследований выделились сорта по скороспелости, дружности формирования ростков, ускоренному размножению, продуктивности, компактности клубней в гнезде и с высоким товарным урожаем – Сочакинур, Хар-Бей и Япон. Возделывание этих сортообразцов по схеме 70×25 и 90×20 см способствует получению товарного урожая высокого качества не менее 43–48 т/га. In 2017–2019, studies were conducted on the study of varieties of sweet potatoes on old-irrigated meadow-gray-earth soils of the Zarafshan valley. The purpose of the research is a comprehensive assessment of sweet potato varieties in the conditions of the Zarafshan valley in terms of early maturity, growth, development, intensive reproduction, yield formation, compactness of tubers in the nest, productivity, yield and keeping quality of tubers and the selection of promising ones, as well as the development of methods of agricultural technology for obtaining high yields for given conditions. The soil is characterized by favorable agrophysical and water properties and low content of humus, nitrate nitrogen, mobile phosphorus and a low-average content of exchange potassium. Eighteen sweet potato varieties were compared. The selected variety samples were studied with a row spacing of 70 and 90 cm with a scheme of 70×25 and 90×20 cm for 1, 2 and 3 seedlings in the nest. To obtain seedlings of sweet potato varieties, 40 tubers were taken and planted on February 20–22 in a film greenhouse at a temperature of 15–18 °C, seeding to a depth of 3–5 cm, the soil moisture was maintained at 65–70%. 7–10 days after planting, the buds began to germinate, and after 43–48 days, seedlings were formed with a height of 12–15 cm, which is ready for planting in the field. Planting seedlings in the field is carried out, as well as other seedlings (tomato, pepper, eggplant) according to the scheme 70x20–25 cm in the second or third decade of April. Growing includes inter-row processing (cultivation), weeding, weed control, top dressing, watering. Harvesting in late September, early October with a potato digger. As a result of the research, varieties were identified in terms of early maturity, sprout formation, accelerated reproduction, productivity, compactness of tubers in the nest and ensuring a high marketable yield – Sochakinur, Xar-Bey, and Japon. The cultivation of these varieties according to the scheme 70×25 and 90×20 cm contributes to the production of a commodity crop at 43–48 t/ha with good qualities.

An Efficient Imine Photocyclization as an Alternative to the Pictet-Spengler Reaction for the Synthesis of AzaBenzannulated Perylenediimide Dyes

2020 ◽  
Author(s):  
Antoine Goujon ◽  
Lou Rocard ◽  
Thomas Cauchy ◽  
Piétrick Hudhomme
Keyword(s):  
Solar Cells ◽  
Visible Light ◽  
Organic Solar Cells ◽  
Reaction Sequence ◽  
Large Scope ◽  
High Yields

AzaBenzannulated PDI (AzaBPDI) dyes were synthesized in high yields via a new reaction sequence involving an imine condensation followed by visible light-induced photocyclization. The large scope and efficiency of this alternative to the Pictet-Spengler reaction is demonstrated, and allows the easy preparation of dimeric AzaBPDI as potential non-fullerene acceptors for organic solar cells.

Scalable Synthesis of Functionalized Ferrocenyl Azides and Amines Enabled by Flow Chemistry

2019 ◽  
Author(s):  
Merlin Kleoff ◽  
Johannes Schwan ◽  
Lisa Boeser ◽  
Bence Hartmayer ◽  
Mathias Christmann ◽  
...  
Keyword(s):  
Reaction Time ◽  
Heterogeneous Reaction ◽  
Reduction Process ◽  
Flow Chemistry ◽  
Subsequent Reaction ◽  
Scalable Synthesis ◽  
High Yields ◽  
Reactor Section

A scalable access to functionalized 1,1’- and 1,2-ferrocenyl azides has been realized in flow. By halogen‒lithium exchange of ferrocenyl halides and subsequent reaction with tosyl azide, a variety of functionalized ferrocenyl azides was obtained in high yields. To allow a scalable preparation of these potentially explosive compounds, an efficient flow protocol was developed accelerating the reaction time to minutes and circumventing accumulation of potentially hazardous intermediates. Switching from homogeneous to triphasic flow amidst process was key for handling a heterogeneous reaction mixture formed after a heated reactor section. The corresponding and synthetically versatile ferrocenyl amines were then prepared by a reliable reduction process.

Stereospecific, Palladium-catalyzed C(sp3)–H Alkenylation and Alkynylation of a Proline Derivative Enabled by 8-Aminoquinoline as a Directing Group

2020 ◽  
Author(s):  
Aleksandra Balliu ◽  
Aaltje Roelofje Femmigje Strijker ◽  
Michael Oschmann ◽  
Monireh Pourghasemi Lati ◽  
Oscar Verho
Keyword(s):  
Carboxylic Acid ◽  
Building Blocks ◽  
Wide Range ◽  
Palladium Catalyzed ◽  
Directing Group ◽  
High Yields ◽  
Vinyl Iodides ◽  
Initial Results

<p>In this preprint, we present our initial results concerning a stereospecific Pd-catalyzed protocol for the C3 alkenylation and alkynylation of a proline derivative carrying the well utilized 8‑aminoquinoline directing group. Efficient C–H alkenylation was achieved with a wide range of vinyl iodides bearing different aliphatic, aromatic and heteroaromatic substituents, to furnish the corresponding C3 alkenylated products in good to high yields. In addition, we were able show that this protocol can also be used to install an alkynyl group into the pyrrolidine scaffold, when a TIPS-protected alkynyl bromide was used as the reaction partner. Furthermore, two different methods for the removal of the 8-aminoquinoline auxiliary are reported, which can enable access to both <i>cis</i>- and <i>trans</i>-configured carboxylic acid building blocks from the C–H alkenylation products.</p>

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