The Experts below are selected from a list of 246 Experts worldwide ranked by ideXlab platform
J. Alberto Marco - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective synthesis of the antiprotozoal lactone passifloricin A and seven isomers thereof.
The Journal of organic chemistry, 2004Co-Authors: Juan Murga, Jorge Garcia‐fortanet, Miguel Carda, J. Alberto MarcoAbstract:The conjugated Delta-Lactone passifloricin A, a natural product with antiprotozoal activity, and seven isomers thereof have been synthesized in enantiopure form. It has been shown in this way that the proposed structure for the natural compound was erroneous. The correct structure is now evidenced. Key steps of the syntheses were asymmetric Brown-type aldehyde allylations and ring-closing metatheses.
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On the structure of passifloricin A: asymmetric synthesis of the Delta-Lactones of (2Z,5S,7R,9S,11S)- and (2Z,5R,7R,9S,11S)tetrahydroxyhexacos-2-enoic acid.
Organic letters, 2003Co-Authors: Jorge Garcia‐fortanet, Juan Murga, Miguel Carda, J. Alberto MarcoAbstract:Stereoselective syntheses of the Delta-Lactone of (2Z,5S,7R,9S,11S)-tetrahydroxyhexacos-2-enoic acid, the structure reported for passifloricin A, and of its (5R)-epimer are described. The creation of all stereogenic centers relied upon Brown's asymmetric allylation methodology. The lactone ring was created via ring-closing metathesis. The NMR data of both synthetic products, however, were different from those of the natural product. The published structure of passifloricin A is thus erroneous and will require further synthetic work to be unambiguously assigned. [structure: see text]
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Stereoselective Synthesis of (+)-Boronolide
The Journal of organic chemistry, 2002Co-Authors: Miguel Carda, Santiago Rodriguez, Beatriz Segovia, J. Alberto MarcoAbstract:The Delta-Lactone boronolide (+)-1, a pharmacologically active, naturally occurring product, has been synthesized in enantiopure form with L-erythrulose as the chiral starting material. The key steps of the synthesis were a highly stereoselective aldol-reduction one-pot sequence, an indium-mediated diastereoselective aldehyde allylation, and a ring-closing metathesis.
Thom Huppertz - One of the best experts on this subject based on the ideXlab platform.
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Acid gelation of reconstituted milk protein concentrate suspensions: Influence of lactose addition
International Dairy Journal, 2016Co-Authors: G. H. Meletharayil, Lloyd Metzger, Hasmukh A. Patel, Thom HuppertzAbstract:Abstract Dispersions (4%, w/w, protein) of reconstituted milk protein concentrate (MPC) powders varying in protein content (35–90% protein on dry matter basis) were standardized to a lactose content that was either unadjusted, 5.6 or 11.2% (w/w) and then heated at 90 °C for 10 min at pH 6.7. Protein interactions in heated milk and rheological properties and microstructure of acid gels formed by the addition of glucono-Delta-Lactone (GDL) were studied. Heat-induced dissociation of κ-casein was influenced by the lactose content of dispersions made from high protein MPC powders. A decrease in elastic moduli (G′) of acid gels at pH 4.6 with increasing MPC protein content was offset by lactose standardization of the dispersions. An increase in gelation pH and in water holding capacity of acid gels was observed with lactose standardization of dispersions. Confocal microscopy revealed a decrease in porosity of acid gels with increasing lactose content of MPC dispersions.
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rheological properties and microstructure of high protein acid gels prepared from reconstituted milk protein concentrate powders of different protein contents
International Dairy Journal, 2015Co-Authors: G. H. Meletharayil, Hasmukh A. Patel, Thom HuppertzAbstract:Abstract Milk protein concentrate (MPC) powders were manufactured by pilot-scale ultrafiltration and diafiltration of skim milk to different protein concentration factors, followed by spray-drying. MPC powders were reconstituted at 7.5% (w/w) protein. Suspensions were subsequently standardised to 15% (w/w) total solids with lactose and heated at 90 °C for 10 min at pH 6.9. Acid gels were prepared from the heated suspensions using glucono-Delta-Lactone. Protein interactions in the heated dispersions and rheological and microstructural properties of the acid gels were studied. Suspensions from the higher protein MPCs showed no dissociation of κ-casein into the serum phase after heating, whereas elastic moduli at pH 4.6 and the gelation pH of the acid gels were higher and water holding capacity and gelation time was lower in acid gels prepared with high-protein MPCs. Confocal microscopy images revealed an increase in the pore size of the acid gels prepared with high-protein MPCs.
G. H. Meletharayil - One of the best experts on this subject based on the ideXlab platform.
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Acid gelation of reconstituted milk protein concentrate suspensions: Influence of lactose addition
International Dairy Journal, 2016Co-Authors: G. H. Meletharayil, Lloyd Metzger, Hasmukh A. Patel, Thom HuppertzAbstract:Abstract Dispersions (4%, w/w, protein) of reconstituted milk protein concentrate (MPC) powders varying in protein content (35–90% protein on dry matter basis) were standardized to a lactose content that was either unadjusted, 5.6 or 11.2% (w/w) and then heated at 90 °C for 10 min at pH 6.7. Protein interactions in heated milk and rheological properties and microstructure of acid gels formed by the addition of glucono-Delta-Lactone (GDL) were studied. Heat-induced dissociation of κ-casein was influenced by the lactose content of dispersions made from high protein MPC powders. A decrease in elastic moduli (G′) of acid gels at pH 4.6 with increasing MPC protein content was offset by lactose standardization of the dispersions. An increase in gelation pH and in water holding capacity of acid gels was observed with lactose standardization of dispersions. Confocal microscopy revealed a decrease in porosity of acid gels with increasing lactose content of MPC dispersions.
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rheological properties and microstructure of high protein acid gels prepared from reconstituted milk protein concentrate powders of different protein contents
International Dairy Journal, 2015Co-Authors: G. H. Meletharayil, Hasmukh A. Patel, Thom HuppertzAbstract:Abstract Milk protein concentrate (MPC) powders were manufactured by pilot-scale ultrafiltration and diafiltration of skim milk to different protein concentration factors, followed by spray-drying. MPC powders were reconstituted at 7.5% (w/w) protein. Suspensions were subsequently standardised to 15% (w/w) total solids with lactose and heated at 90 °C for 10 min at pH 6.9. Acid gels were prepared from the heated suspensions using glucono-Delta-Lactone. Protein interactions in the heated dispersions and rheological and microstructural properties of the acid gels were studied. Suspensions from the higher protein MPCs showed no dissociation of κ-casein into the serum phase after heating, whereas elastic moduli at pH 4.6 and the gelation pH of the acid gels were higher and water holding capacity and gelation time was lower in acid gels prepared with high-protein MPCs. Confocal microscopy images revealed an increase in the pore size of the acid gels prepared with high-protein MPCs.
Miguel Carda - One of the best experts on this subject based on the ideXlab platform.
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Stereoselective synthesis of the antiprotozoal lactone passifloricin A and seven isomers thereof.
The Journal of organic chemistry, 2004Co-Authors: Juan Murga, Jorge Garcia‐fortanet, Miguel Carda, J. Alberto MarcoAbstract:The conjugated Delta-Lactone passifloricin A, a natural product with antiprotozoal activity, and seven isomers thereof have been synthesized in enantiopure form. It has been shown in this way that the proposed structure for the natural compound was erroneous. The correct structure is now evidenced. Key steps of the syntheses were asymmetric Brown-type aldehyde allylations and ring-closing metatheses.
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On the structure of passifloricin A: asymmetric synthesis of the Delta-Lactones of (2Z,5S,7R,9S,11S)- and (2Z,5R,7R,9S,11S)tetrahydroxyhexacos-2-enoic acid.
Organic letters, 2003Co-Authors: Jorge Garcia‐fortanet, Juan Murga, Miguel Carda, J. Alberto MarcoAbstract:Stereoselective syntheses of the Delta-Lactone of (2Z,5S,7R,9S,11S)-tetrahydroxyhexacos-2-enoic acid, the structure reported for passifloricin A, and of its (5R)-epimer are described. The creation of all stereogenic centers relied upon Brown's asymmetric allylation methodology. The lactone ring was created via ring-closing metathesis. The NMR data of both synthetic products, however, were different from those of the natural product. The published structure of passifloricin A is thus erroneous and will require further synthetic work to be unambiguously assigned. [structure: see text]
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Stereoselective Synthesis of (+)-Boronolide
The Journal of organic chemistry, 2002Co-Authors: Miguel Carda, Santiago Rodriguez, Beatriz Segovia, J. Alberto MarcoAbstract:The Delta-Lactone boronolide (+)-1, a pharmacologically active, naturally occurring product, has been synthesized in enantiopure form with L-erythrulose as the chiral starting material. The key steps of the synthesis were a highly stereoselective aldol-reduction one-pot sequence, an indium-mediated diastereoselective aldehyde allylation, and a ring-closing metathesis.
Amy R. Howell - One of the best experts on this subject based on the ideXlab platform.
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Cross metathesis of alpha-methylene lactones II: gamma- and Delta-Lactones.
Organic letters, 2007Co-Authors: Ravinder Raju, Laura J. Allen, Christopher D. Taylor, Amy R. HowellAbstract:[reaction: see text] The cross metathesis reactivities of alpha-methylene-gamma-butyrolactone and an alpha-methylene-Delta-Lactone have been investigated. alpha-Methylene-gamma-butyrolactone undergoes rapid and efficient olefin isomerization in the presence of second-generation metathesis catalysts. However, cross metathesis can be achieved with the additive 2,6-dichlorobenzoquinone. In contrast, the alpha-methylene-Delta-Lactone neither isomerizes nor couples under similar conditions.