ABSTRACT
The ICH M7 Option 4 control of (potentially) mutagenic impurities is based on the use of scientific principles in lieu of routine analytical testing. This approach can reduce the burden of analytical testing without compromising patient safety, provided a scientifically rigorous approach is taken which is backed up by sufficient theoretical and/or analytical data. This paper introduces a consortium-led initiative and offers a proposal on the supporting evidence that could be presented in regulatory submissions.
Subject(s)
Drug Contamination/prevention & control , Mutagenicity Tests/standards , Mutagens/toxicity , Pharmaceutical Preparations/standards , Technology, Pharmaceutical/standards , Computer Simulation , Humans , Mutagenicity Tests/methods , Pharmaceutical Preparations/chemical synthesis , Practice Guidelines as Topic , Quality Control , Quantitative Structure-Activity Relationship , Risk AssessmentABSTRACT
Photolysis of 1-(3-alkynoxy)-9,10-anthraquinones in deoxygenated methanol leads to moderate yields (35-45%) of 3-alkynals along with the unexpected formation of diacetals. Reaction of these 3-alkynals with Grignard and Wittig reagents occurs nearly quantitatively without rearrangement to their 2,3-dienal isomers.
ABSTRACT
Two syntheses of 3-substituted-4-amino-[3,2-c]thienopyridines have been developed to replace the standard literature route to these compounds, which uses unattractive conditions involving azide and high temperatures. The first synthesis utilizes a Friedel-Crafts reaction as its key ring-forming step, whereas the second route relies on an unprecedented intramolecular reductive cyclization between a nitroolefin and a nitrile as its key ring-forming step. The development and optimization of each 3-substituted-4-amino-[3,2-c]thienopyridine synthesis is discussed and a comparison of the routes is presented.
Subject(s)
Pyridines/chemical synthesis , Carbon Dioxide/chemistry , Cyclization , Halogens/chemistry , Metals/chemistry , Oxidation-Reduction , Pyridines/chemistry , Thiophenes/chemistryABSTRACT
The cross-coupling of geometrically defined (E)- and (Z)-alkenyl- and styrylsilanolates with a wide variety of aromatic and heteroaromatic chlorides has been achieved. Under catalysis by bulky, biphenyl-derived phosphines and allylpalladium chloride, the (preformed, stable) potassium salts of di-, tri- and tetrasubstituted alkenyldimethylsilanols undergo high yielding and highly stereospecific coupling to aryl chlorides in THF or dioxane. A variety of functional groups are compatible with these reaction conditions including nitro, ester, ketone, and nitrile. Both (E)- and (Z)-alkenylsilanolates coupled with nearly identical rate and efficiency.
Subject(s)
Chlorides/chemistry , Palladium/chemistry , Alkylation , Catalysis , Ligands , Molecular Structure , StereoisomerismABSTRACT
[reaction: see text] A [3 + 2] cycloaddition reaction between alkynyldimethylsilyl ethers and aryl and alkyl nitrile oxides to produce isoxazolylsilanols has been developed. The cross-coupling reactions of these heterocyclic silanols with a variety of aryl iodides affords 3,4,5-trisubstituted isoxazoles. This sequential process allows for rapid variation of substituents at the 3, 4, and 5 positions of the isoxazole.
Subject(s)
Isoxazoles/chemical synthesis , Silicon/chemistry , Isoxazoles/chemistry , Magnetic Resonance Spectroscopy , Spectrophotometry, UltravioletABSTRACT
[reaction: see text] A mild and general palladium-catalyzed insertion of 1,2-diethoxy-1,1,2,2-tetramethyldisilane into a variety of aryl bromides affords the aryldimethylsilyl ethers in high yields. Hydrolysis of the ethers under pH-optimized conditions results in the exclusive formation of the desired aryldimethylsilanols.
Subject(s)
Palladium/chemistry , Silanes/chemical synthesis , Alkylation , Bromides/chemistry , Catalysis , Hydrogen-Ion Concentration , Hydrolysis , Ligands , Models, ChemicalABSTRACT
A substituted anthraquinone (AQ), previously shown to photochemically generate benzaldehyde in methanol solution, was attached to a commercially available resin via an 11 carbon tether and an amide bond. Photolysis of the polymer-bound AQ with visible or 350 nm UV light resulted in the formation of benzaldehyde in yields of 50-55% as determined by HPLC. The phenolic positions in the polymer were then alkylated using benzyl bromide and 1-iodo-3-(4-nitrophenyl)propane in a coupling reaction with K(2)CO(3) as a base and a solution-phase proton shuttle. Photolysis of these alkylated polymers resulted in the formation of benzaldehyde (54-89%) and 3-(4-nitrophenyl)-propanal (58-67%). The yields of both aldehydes dropped considerably with subsequent realkylation and photolysis, and the polymer beads began to show signs of deterioration. This is the first time that aldehydes have been made photochemically on a solid-supported phase.
