Search

The objective of this work was to investigate the effect of dietary bypass fat on milk composition of Bergamasca dairy ewes. The experiment was carried out at the Ewe Milk Production Research Unit of the College of Veterinary Medicine and Animal Science of São Paulo State University. Eighty Bergamasca ewes were divided into two groups and fed one of two diets: A - balanced diet (concentrate + corn silage); or B - same diet as A, with bypass fat (35 g/ewe/day) added to the concentrate. Lambs were kept with their mothers on pasture during daytime and were separated at night. After the morning milking, the lambs were returned to their mothers and weaned at 45 days of age. The ewes were machine-milked for 60 days. Milk samples were collected once weekly for analysis of lactose, protein, fat and total solids. The data were analyzed by one-way analysis of variance. For the first 45 days of lactation, significant differences (P<.05) were observed for protein and lactose, with ewes fed diet B having higher means, whereas differences were not observed (P>.05) for fat and total solids. After 45 days of lactation, significant differences (P<.05) were found only for fat and lactose, which may be explained by the higher milk production of ewes fed diet B because some researchers have reported a negative correlation between production and concentration of milk constituents. [ABSTRACT FROM AUTHOR]

Several factors that contribute to variation in production and quality of ewe milk have been described, such as environment, breed, age of ewe, lactation stage, number of lambs or milking techniques, sanitary condition and udder infections, herd management and nutritional level during gestation and lactation. The objective of this project was to evaluate two milk production systems and their effect on milk chemical composition using 87 Bergamasca ewes. Ewes in one group were separated from their lambs 48 h after birth, while ewes in the second group were kept with their lambs until the lambs were weaned at 60 days of age. All ewes were machine-milked for a period of 90 days. Milk samples were collected once a week for analyses of lactose, protein, fat and total solids using infrared. The analyses were carried out at the Milk Cattle Breeding Management Technology Center, ESALQ/USP, Piracicaba, São Paulo. The data were statistically analyzed using the GLM procedure of SAS. Differences in production of fat, protein, lactose and total solids contents during the whole lactation were observed between the two systems (P<.05). Fat content of the milk from the ewe group without lambs was higher (5.51%) than the ewe group with lambs (3.74%). Differences in protein content of the milk were also found; however, average protein values were within levels reported in previous studies. [ABSTRACT FROM AUTHOR]

Little is known in Brazil about milk production of ewes. As wool and meat production have become important activities in the country, an increasing interest in milk production is observed. Thus, the objective of the present work is to evaluate the effect of the use of bypass fat in the diet of Bergamasca dairy ewes on milk production. Eighty ewes were divided into 2 blocks according to parturition and age. Within each block, half of the animals received either one of two treatments: A - balanced diet (concentrate + corn silage) without bypass fat; and B - same diet as in A with added bypass fat (35g/ewe/day). In both blocks, the lambs were kept with their mothers in pasture during daytime and were separated at night. The lambs were returned to their mothers after the morning milking and were weaned at 45 days of age. The ewes were machine-milked starting 48 hours after parturition, once a day, at 7h A.M., for 60 days. Diets were isoenergetic and isonitrogenous, containing 22% CP and 66% TDN on a dry-matter basis. The statistical analysis was performed by means of SAEG 9.0 (System for Statistical and Genetic Analyses). Statistical differences were not observed (P>.05) between treatments for average daily milk production until 45 days; however, after 45 days, treatment B showed a higher (P<.05) milk yield in comparison to A (540 vs 502 g/ewe/day). This result may be attributed to the use of diet with bypass fat, which supposedly provided better absorption of unsaturated fatty acids in the small intestine. [ABSTRACT FROM AUTHOR]

Most of Brazilian breeds present capability for meat or wool production, but it is possible to find animals with dairy properties. Bergamasca ewes, for example, introduced in Brazil in 1940, are raised in the Northeast for meat production. Considering their Italian origin, they could be used for milk production; however, the amount of milk produced by lactation and its characteristics are not well known. In view of this, the objective of the present work, carried out at the Ewe Milk Production Research Unit of the College of Veterinary Medicine and Animal Science of the São Paulo State University (UNESP), is to evaluate the effect of the different management systems on milk production of Bergamasca ewes. Eighty seven ewes were used and submitted to two milk production systems. In the group without lambs, these were separated from their mothers 48h after birth, while, in the mixed group, lambs were kept with their mothers until to 60 days of age, when they were weaned. Both ewes from the group without lambs and from the mixed group were machine-milked for a period of 90 days and milk production was daily measured during the whole experimental period. The statistical analysis was performed by means of the GLM procedure of the Statistical Analysis System (SAS, 1985). Ewes managed in the group without lamb presented higher (P<.05) daily average milk production in comparison to the mixed group. This difference may be explained, in part, by milk injection inhibition during machine-milking. In the beginning of lactation, the absence of a proper sign during machine-milking, which is usually present when females are nursing their lambs, inhibits the release of ocytocin and milk ejection reflex. [ABSTRACT FROM AUTHOR]

We disclose herein our evaluation of competitive (hetero)aryl-X (X: Br>Cl>OTf) reactivity preferences in bisphosphine/Ni-catalyzed C-N cross-coupling catalysis, using furfurylamine as a prototypical nucleophile, and employing DalPhos and DPPF as representative ancillary ligands with established efficacy. Beyond this general (pseudo)halide ranking, other intriguing structure-reactivity trends were noted experimentally, including the unexpected observation that bulky alkyl (e. g., R=tBu) substitution in para-R-aryl-X electrophiles strongly discourages (pseudo)halide reactivity relative to smaller substituents (e. g., nBu, Et, Me), despite being both remote from, and having a similar electronic influence on, the reacting C-X bond; such effects on nickel oxidative addition have not been documented previously and were not observed in our comparator reactions presented herein involving palladium. Density functional theory modeling of such PhPAd-DalPhos/Ni-catalyzed C-N cross-couplings revealed the origins of competitive turnover of C-Br over C-Cl, and possible ways in which bulky para-alkyl substitution might discourage net electrophile uptake/turnover, leading to inversion of halide selectivity., (© 2024 The Author(s). Chemistry - A European Journal published by Wiley-VCH GmbH.)

A comparative experimental and computational study examining the interplay of the ancillary ligand structure and Ni oxidation state in the Ni-catalyzed C(sp 2 )-O cross-coupling of (hetero)aryl chlorides and primary or secondary aliphatic alcohols is presented, focusing on PAd-DalPhos ( L1 )-, CyPAd-DalPhos ( L2 )-, PAd2-DalPhos ( L3 )-, and DPPF ( L4 )-ligated [( L )NiCl] n ( n = 1 or 2) and ( L )Ni( o -tol)Cl precatalysts. Both L1 and L2 were found to outperform the other ligands examined, with the latter proving to be superior overall. While Ni(II) precatalysts generally outperformed Ni(I) species, in some instances the catalytic abilities of Ni(I) precatalysts were competitive with those of Ni(II). Density-functional theory calculations indicate the favorability of a Ni(0)/Ni(II) catalytic cycle featuring turnover-limiting C-O bond reductive elimination over a Ni(I)/Ni(III) cycle involving turnover-limiting C-Cl oxidative addition.

Nickel-catalyzed cross-couplings of (hetero)aryl electrophiles with a diversity of nucleophiles (nitrogen, oxygen, carbon, and others) have evolved into competitive alternatives to well-established palladium- and copper-based protocols for the synthesis of (hetero)aryl products, including (hetero)anilines and (hetero)aryl ethers. A survey of the literature reveals that the use of cage phosphine (CgP) 'DalPhos' (DALhousie PHOSphine) bisphosphine-type ligands operating under thermal conditions currently offers the most broad substrate scope in nickel-catalyzed cross-couplings of this type, especially involving (hetero)aryl chlorides and phenol-derived electrophiles. The development and application of these DalPhos ligands is described in a ligand-specific manner that is intended to serve as a guide for the synthetic chemistry end-user., Competing Interests: The authors declare the following competing financial interests: Dalhousie University has filed patents on the DalPhos ancillary ligands and derived nickel pre-catalysts used in this work, from which royalty payments may be derived., (This journal is © The Royal Society of Chemistry.)

We report a versatile method for cross-coupling of NH -sulfoximines with (hetero)aryl chlorides, as well as bromide and sulfonate electrophiles, that makes use of the air-stable, commercial precatalyst (PhPAd-DalPhos)Ni( o -tol)Cl. Under optimized conditions a diverse electrophile scope is established, including the N -arylation of the pharmaceutical Clozapine. While 5 mol % Ni and 80 °C are commonly employed in this chemistry, successful examples utilizing 1 mol % Ni and/or 25 °C are presented. Competition experiments establish the superiority of NH -sulfoximine over primary sulfonamide as nucleophiles under these conditions.

We report a versatile method for C2 functionalization of (benz)oxazoles and (benzo)thiazoles employing a tert -butylimino-tri(pyrrolidino)phosphorane/sodium trifluoroacetate (BTPP/NaTFA) "dual-base" system in combination with an air-stable Ni(II) precatalyst containing either CyPAd-DalPhos or PhPAd-DalPhos. These catalyst systems enable access to a reaction scope that encompasses a range of challenging oxidative addition partners, including (hetero)aryl chlorides as well as pivalates, tosylates, and other related phenol derivatives. The utility of this method is demonstrated through the derivatization of an active pharmaceutical ingredient and 5 mmol synthesis of a thiazole derivative.

A systematic evaluation of competitive bisphosphine/Ni-catalyzed C-N versus C-O cross-couplings involving model compounds enabled development of hitherto unknown chemoselective O- and N-arylation of amino alcohols with (hetero)aryl chloride electrophiles, without recourse to protection group chemistry. Use of the CyPAd-DalPhos pre-catalyst C2 enabled particularly challenging O-arylation chemoselectivity in amino alcohols featuring branched primary and secondary alkylamine groups, while selective N-arylation was observed in substrates featuring less-hindered linear alkylamine and aniline reacting groups. Useful reaction scope in the (hetero)aryl chloride was achieved throughout, and the ability to conduct such transformations using benchtop handling of materials is demonstrated., (© 2023 The Authors. Angewandte Chemie International Edition published by Wiley-VCH GmbH.)

A systematic competitive evaluation of the DalPhos ligand family in nickel-catalyzed N-arylation chemistry is reported, involving primary (linear and branched) and secondary alkylamines, as well as a primary five-membered heteroarylamine (aminopyrazole), in combination with a diverse set of test electrophiles and bases (NaOtBu, K 2 CO 3 , DBU/NaTFA). In addition to providing optimal ligand/catalyst identification, and bringing to light methodology limitations (e. g., unwanted C-O cross-coupling with NaOtBu), our survey enabled the development of the first efficient catalyst system for heteroatom-dense C-N cross-coupling of aminopyrazoles and related nucleophiles with (hetero)aryl chlorides by use of an amine 'dual-base' system., (© 2022 Wiley-VCH GmbH.)

Notwithstanding recent developments in nickel-catalyzed C-O cross-coupling chemistry, such transformations of substituted phenols and (hetero)aryl chlorides with a useful reaction scope have yet to be reported. In this work, we disclose the results of catalyst screening that allowed the identification of PhPAd-DalPhos/NiCOD 2 as an effective catalyst system under thermal conditions for the O-arylation of substituted phenols with chloropyridine-type electrophiles, leading to pyridyl- O -aryl frameworks that are found in active pharmaceutical ingredients.

We report on our successful development of the first metal-catalyzed mono-α-arylation of carbonyl compounds employing a soluble organic base. The scope of these Ni/DalPhos-catalyzed transformations encompasses a range of (hetero)aryl halides (Cl, Br, I) and phenol-derived electrophiles (sulfonates, carbonates, carbamates, sulfamates), including active pharmaceutical ingredients (chloroquine, clozapine), in combination with the typically problematic feedstock small molecule substrates acetone, dimethylacetamide, and for the first time with any metal catalyst/base, ethyl acetate., (© 2022 Wiley-VCH GmbH.)

4-Amino-1,8-naphthalimides, potentially useful fluorescent probes in biological applications, are prepared via Ni(cod) 2 /IPr-catalyzed cross-couplings between 4-chloro-1,8-naphthalimide electrophiles and α,α,α-trisubstituted, primary alkylamines at room temperature. This method represents the first synthesis of 4-amino-1,8-naphthalimides using Ni-catalyzed C-N cross-coupling and provides the first examples of 4-amino-1,8-naphthalimides incorporating such bulky primary alkylamines, thereby highlighting the utility of Ni-catalyzed processes in synthesizing naphthalimide scaffolds that were inaccessible using established methods (S N Ar; Pd or Cu catalysis).

The C-N cross-coupling of (hetero)aryl (pseudo)halides with NH substrates employing nickel catalysts and organic amine bases represents an emergent strategy for the sustainable synthesis of (hetero)anilines. However, unlike protocols that rely on photoredox/electrochemical/reductant methods within Ni I/III cycles, the reaction steps that comprise a putative Ni 0/II C-N cross-coupling cycle for a thermally promoted catalyst system using organic amine base have not been elucidated. Here we disclose an efficient new nickel-catalyzed protocol for the C-N cross-coupling of amides and 2'-(pseudo)halide-substituted acetophenones, for the first time where the (pseudo)halide is chloride or sulfonate, which makes use of the commercial bisphosphine ligand PAd2-DalPhos (L4) in combination with an organic amine base/halide scavenger, leading to 4-quinolones. Room-temperature stoichiometric experiments involving isolated Ni 0, I, and II species support a Ni 0/II pathway, where the combined action of DBU/NaTFA allows for room-temperature amide cross-couplings., (© 2022 Wiley-VCH GmbH.)

The Ni-catalyzed N-arylation of β-fluoroalkylamines with broad scope is reported for the first time. Use of the air-stable pre-catalyst (PAd2-DalPhos)Ni(o-tol)Cl allows for reactions to be conducted at room temperature (25 °C, NaOtBu), or by use of a commercially available dual-base system (100 °C, DBU/NaOTf), to circumvent decomposition of the N-(β-fluoroalkyl)aniline product. The mild protocols disclosed herein feature broad (hetero)aryl (pseudo)halide scope (X=Cl, Br, I, and for the first time phenol-derived electrophiles), encompassing base-sensitive substrates and enantioretentive transformations, in a manner that is unmatched by any previously reported catalyst system., (© 2020 Wiley-VCH GmbH.)

The development of Ni-catalyzed C-N cross-couplings of sulfonamides with (hetero)aryl chlorides is reported. These transformations, which were previously achievable only with Pd catalysis, are enabled by use of air-stable (L)NiCl(o-tol) pre-catalysts (L=PhPAd-DalPhos and PAd2-DalPhos), without photocatalysis. The collective scope of (pseudo)halide electrophiles (X=Cl, Br, I, OTs, and OC(O)NEt 2 ) demonstrated herein is unprecedented for any reported catalyst system for sulfonamide C-N cross-coupling (Pd, Cu, Ni, or other). Preliminary competition experiments and relevant coordination chemistry studies are also presented., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Treatment of (PN)NiX (X = NHdipp or OtBu; PN = N-phosphinoamidinate ligand) with Me2PhSiH in benzene solvent afforded the crystallographically characterized, antifacial-coordinated, dinuclear species 1, the formation of which corresponds to the hitherto unknown net Ni-H addition of two equivalents of the putative (PN)NiH intermediate across C[double bond, length as m-dash]C units within a single benzene molecule. Computational analysis supports the view of 1 as being comprised of two cationic (PN)NiII fragments ligated by a substituted butadiene dianion μ2-η3:η3-C6H82- bridging group. Also described is the formation and characterization of three-coordinate (PN)Ni(alkyl) complexes stabilized by β-agostic (alkyl = Et, 2; n-Bu, 3; n-hexyl, 4) or γ-agostic (alkyl = neopentyl, 5) interactions, and our efforts to employ 2 and 3 as synthons for the generation of (PN)NiHvia β-hydride elimination. Notably, compound 5 represents both the first crystallographically characterized three-coordinate Ni-alkyl complex featuring a heterobidentate ligation, and the first neutral γ-agostic NiII-alkyl complex.

A comparative study of the performance of (PN)M(N(SiMe3)2) (M = Mn, Fe, Co, and Ni) pre-catalysts supported by N-phosphinoamidinate ligation, as well as M(N(SiMe3)2)n (M = Li, Na, K, Mn, Fe, and Co) pre-catalysts, in the hydrosilative reduction of selected tertiary amide test substrates using PhSiH3 is reported. Encouraged by the performance observed herein for (PN)Ni(N(SiMe3)2) in the reduction of both N,N-dibenzylbenzamide and N,N-diisopropylbenzamide, further competitive testing involving the known complex (PN)Ni(NHdipp) (dipp = 2,6-diisopropylphenyl), as well as the new and crystallographically characterized mononuclear complexes (PN)Ni(OR) (R = 2,6-dimethylphenyl or tBu), revealed (PN)Ni(OtBu) to be particularly effective in such reduction chemistry, including transformations involving the secondary amides N-benzylbenzamide and caprolactam.

Base-metal catalysts capable of enabling the assembly of heteroatom-dense molecules by cross-coupling of primary heteroarylamines and (hetero)aryl chlorides, while sought-after given the ubiquity of unsymmetrical di(hetero)arylamino fragments in pharmacophores, are unknown. Herein, we disclose the new "double cage" bisphosphine PAd2-DalPhos (L2). The derived air-stable Ni II pre-catalyst C2 functions well at low loadings in challenging test C-N cross-couplings with established substrates, and facilitates the first Ni-catalyzed C-N cross-couplings of primary five- or six-membered ring heteroarylamines and activated (hetero)aryl chlorides, with synthetically useful scope that is competitive with Pd catalysis., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The base metal-catalyzed C-N cross-coupling of bulky α,α,α-trisubstituted primary alkylamines with (hetero)aryl electrophiles represents a challenging and under-developed class of transformations that is of significant potential utility, including in the synthesis of lipophilic active pharmaceutical ingredients. Herein, we report that a new, air-stable Ni(II) pre-catalyst incorporating the optimized ancillary ligand PhPAd-DalPhos enables such transformations of (hetero)aryl chloride, bromide, and tosylate electrophiles to be carried out for the first time with substrate scope rivalling that achieved using state-of-the-art Pd catalysts, including room temperature cross-couplings of (hetero)aryl chlorides that are unprecedented for any catalyst (Pd, Ni, or other)., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The use of (L)Ni( o-tolyl)Cl precatalysts (L = PAd-DalPhos or CyPAd-DalPhos) enables the C( sp 2 )-O cross-coupling of primary, secondary, or tertiary aliphatic alcohols with (hetero)aryl electrophiles, including unprecedented examples of such nickel-catalyzed transformations employing (hetero)aryl chlorides, sulfonates, and pivalates. In addition to offering a competitive alternative to palladium catalysis, this work establishes the feasibility of utilizing ancillary ligation as a complementary means of promoting challenging nickel-catalyzed C( sp 2 )-O cross-couplings, without recourse to precious-metal photoredox catalytic methods.

A new (N-phosphinoamidinate)manganese complex is shown to be a useful pre-catalyst for the hydrosilative reduction of carbonyl compounds, and in most cases at room temperature. The Mn-catalyzed reduction of tertiary amides to tertiary amines, with a useful scope, is demonstrated for the first time by use of this catalyst, and is competitive with the most effective transition-metal catalysts known for such transformations. Ketones, aldehydes, and esters were also successfully reduced under mild conditions by using this new Mn catalyst., (© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)