scholarly journals Gold(I)-Catalyzed Coupling Reactions for the Synthesis of Diverse Small Molecules Using the Build/Couple/Pair Strategy

2009 ◽  
Vol 131 (15) ◽  
pp. 5667-5674 ◽  
Author(s):  
Tuoping Luo ◽  
Stuart L. Schreiber
Keyword(s):  
Small Molecules ◽  
Coupling Reactions ◽  
Couple Pair

scholarly journals Protecting group-free, selective cross-coupling of alkyltrifluoroborates with borylated aryl bromides via photoredox/nickel dual catalysis

2015 ◽  
Vol 112 (39) ◽  
pp. 12026-12029 ◽  
Author(s):  
Yohei Yamashita ◽  
John C. Tellis ◽  
Gary A. Molander
Keyword(s):  
Small Molecules ◽  
Functional Group ◽  
Cross Coupling ◽  
Differential Protection ◽  
Coupling Reactions ◽  
Protecting Group ◽  
Cross Coupling Reactions ◽  
Aryl Bromides ◽  
Rapid Construction ◽  
Metal Catalyzed

Orthogonal reactivity modes offer substantial opportunities for rapid construction of complex small molecules. However, most strategies for imparting orthogonality to cross-coupling reactions rely on differential protection of reactive sites, greatly reducing both atom and step economies. Reported here is a strategy for orthogonal cross-coupling wherein a mechanistically distinct activation mode for transmetalation of sp3-hybridized organoboron reagents enables C-C bond formation in the presence of various protected and unprotected sp2-hybridized organoborons. This manifold has the potential for broad application, because orthogonality is inherent to the activation mode itself. The diversification potential of this platform is shown in the rapid elaboration of a trifunctional lynchpin through various transition metal-catalyzed processes without nonproductive deprotection or functional group manipulation steps.

scholarly journals Skeletally Diverse Small Molecules Using a Build/Couple/Pair Strategy

2009 ◽  
Vol 11 (7) ◽  
pp. 1559-1562 ◽  
Author(s):  
Takuya Uchida ◽  
Manuela Rodriquez ◽  
Stuart L. Schreiber
Keyword(s):  
Small Molecules ◽  
Couple Pair

Combining the Petasis 3-Component Reaction with Multiple Modes of Cyclization: A Build/Couple/Pair Strategy for the Synthesis of Densely Functionalized Small Molecules

2014 ◽  
Vol 17 (1) ◽  
pp. 19-23 ◽  
Author(s):  
Thomas Flagstad ◽  
Mette R. Hansen ◽  
Sebastian T. Le Quement ◽  
Michael Givskov ◽  
Thomas E. Nielsen
Keyword(s):  
Small Molecules ◽  
Multiple Modes ◽  
Couple Pair

scholarly journals Ligand-Controlled Regiodivergent Palladium-Catalyzed Hydrogermylation of Ynamides

2020 ◽  
Author(s):  
Vincent Debrauwer ◽  
Aneta Turlik ◽  
Lénaïc Rummler ◽  
Alessandro Prescimone ◽  
Nicolas Blanchard ◽  
...  
Keyword(s):  
Small Molecules ◽  
Functional Group ◽  
Cross Coupling ◽  
Building Blocks ◽  
Coupling Reactions ◽  
Heterocyclic Chemistry ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Pi System

Ynamides are fascinating small molecules with complementary reactivities under radical, ionic and metal-catalyzed conditions. We report herein synthetic and DFT investigations of palladium-catalyzed ligand-controlled regiodivergent hydro-metallation reactions of ynamides. Germylated and stannylated enamides are obtained with excellent alpha,<i>E</i>- or beta,<i>E</i>-selectivities and a broad functional group tolerance. Such a regiodivergent palladium-catalyzed process is unique in ynamide chemistry and allows for the elaboration of metallated-enamides that are useful building blocks for cross-coupling reactions or heterocyclic chemistry. DFT calculations fully support the experimental data and demonstrate the crucial roles of the <i>trans</i>-geometry of the [H-Pd(L)-Ge] complex, as well as of the steric requirements of the phosphine ligand. In addition, the prevalence of a hydro-palladation pathway over a metal-palladation of the pi system of the ynamide was demonstrated.

scholarly journals Ligand-Controlled Regiodivergent Palladium-Catalyzed Hydrogermylation of Ynamides

2020 ◽  
Author(s):  
Vincent Debrauwer ◽  
Aneta Turlik ◽  
Lénaïc Rummler ◽  
Alessandro Prescimone ◽  
Nicolas Blanchard ◽  
...  
Keyword(s):  
Small Molecules ◽  
Functional Group ◽  
Cross Coupling ◽  
Building Blocks ◽  
Coupling Reactions ◽  
Heterocyclic Chemistry ◽  
Cross Coupling Reactions ◽  
Palladium Catalyzed ◽  
Metal Catalyzed ◽  
Pi System

Ynamides are fascinating small molecules with complementary reactivities under radical, ionic and metal-catalyzed conditions. We report herein synthetic and DFT investigations of palladium-catalyzed ligand-controlled regiodivergent hydro-metallation reactions of ynamides. Germylated and stannylated enamides are obtained with excellent alpha,<i>E</i>- or beta,<i>E</i>-selectivities and a broad functional group tolerance. Such a regiodivergent palladium-catalyzed process is unique in ynamide chemistry and allows for the elaboration of metallated-enamides that are useful building blocks for cross-coupling reactions or heterocyclic chemistry. DFT calculations fully support the experimental data and demonstrate the crucial roles of the <i>trans</i>-geometry of the [H-Pd(L)-Ge] complex, as well as of the steric requirements of the phosphine ligand. In addition, the prevalence of a hydro-palladation pathway over a metal-palladation of the pi system of the ynamide was demonstrated.

Gap junctions in the prothoracic glands of the tobacco hornworm, Manduca sexta

1992 ◽  
Vol 50 (1) ◽  
pp. 706-707
Author(s):  
Ji-da Dai ◽  
M. Joseph Costello ◽  
Lawrence I. Gilbert
Keyword(s):  
Gap Junctions ◽  
Small Molecules ◽  
Manduca Sexta ◽  
Freeze Fracture ◽  
Cell Communication ◽  
Cellular Level ◽  
Thin Sections ◽  
Prothoracic Glands ◽  
Polyhydroxylated Steroids ◽  
Stimulation Of

Insect molting and metamorphosis are elicited by a class of polyhydroxylated steroids, ecdysteroids, that originate in the prothoracic glands (PGs). Prothoracicotropic hormone stimulation of steroidogenesis by the PGs at the cellular level involves both calcium and cAMP. Cell-to-cell communication mediated by gap junctions may play a key role in regulating signal transduction by controlling the transmission of small molecules and ions between adjacent cells. This is the first report of gap junctions in the PGs, the evidence obtained by means of SEM, thin sections and freeze-fracture replicas.

Fusion and Fission Processes in Exocytosis: Possible Roles for Synexin and Osmotic Lysis in the Two Events

1980 ◽  
Vol 38 ◽  
pp. 594-597
Author(s):  
H.B. Pollard ◽  
C.E. Creutz ◽  
C.J. Pazoles ◽  
J.H. Scott
Keyword(s):  
Small Molecules ◽  
Chromaffin Cells ◽  
Adrenal Glands ◽  
General Concept ◽  
Extracellular Calcium ◽  
Large Protein ◽  
Granule Membrane ◽  
Osmotic Lysis ◽  
Per Se ◽  
Chemical Evidence

Exocytosis is a general concept describing secretion of enzymes, hormones and transmitters that are otherwise sequestered in intracellular granules. Chemical evidence for this concept was first gathered from studies on chromaffin cells in perfused adrenal glands, in which it was found that granule contents, including both large protein and small molecules such as adrenaline and ATP, were released together while the granule membrane was retained in the cell. A number of exhaustive reviews of this early work have been published and are summarized in Reference 1. The critical experiments demonstrating the importance of extracellular calcium for exocytosis per se were also first performed in this system (2,3), further indicating the substantial service given by chromaffin cells to those interested in secretory phenomena over the years.

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