Expedient Iron‐Catalyzed Coupling of Alkyl,Benzyl and Allyl Halides with Arylboronic Esters

While attractive, the iron‐catalyzed coupling of arylboron reagents with alkyl halides typically requires expensive or synthetically challenging diphosphine ligands. Herein, we show that primary and secondary alkyl bromides and chlorides, as well as benzyl and allyl halides, can be coupled with arylboronic esters, activated with alkyllithium reagents, by using very simple iron‐based catalysts. The catalysts used were either adducts of inexpensive and widely available diphosphines or, in a large number of cases, simply [Fe(acac)₃] with no added co‐ ligands. In the former case, preliminary mechanistic studies highlight the likely involvement of iron(I)–phosphine intermediates.     

Synthesis of nickel base alloys for use as magnetic standards

The goal of this research is to prepare a series of alloys having sharp, reproducible magnetic transitions for calibrating temperature in thermogravimetry from the magnetic transition temperature of pure cobalt (1121°C) to below room temperature.Alloys in the Ni-Co and Ni-Cu systems were prepared by the thermal decomposition of coprecipitated oxalates in argon. The alloys were subsequently annealed under 5% hydrogen.Magnetic transition temperatures were measured using simultaneous thermomagnetometry/differential thermal analysis. Transition temperatures were corrected using well known meltingpoint standards. Magnetic transition temperatures along with precision are reported as a function of composition.     

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Synthetic entries to substituted bicyclic pyridones

The synthesis of 6,6- and 5,6-bicyclic pyridone scaffolds has been completed using (i) an intramolecular Mitsunobu reaction and/or (ii) hydrolysis of a bicyclic pyridinium salt intermediate. Regioselective functionalization of the pyridone ring has been achieved via either direct lithiation or use of the "halogen dance" reaction. Suzuki coupling then allows introduction of aryl units at C(7)/C(9) or C(8) onto the bicyclic pyridone scaffold at either an early or late stage in the synthetic sequence. Suzuki couplings involving iodopyridinium intermediates are particularly effective.     

3-oxo-3-phosphapentopyranoses

Addition of methyl phosphinate to 2(R)-methoxy 3-oxapentanedial gives all eight possible diastereoisomeric 3-phosphapentopyranoses in very poor yield. Structures and stereochemistry are assigned on the basis of ¹H, ³¹P, NMR, and mass spectroscopy of their acetates. © 1996 John Wiley & Sons, Inc.     

Ethyl and isopropyl 4‐ferrocenylbenzoate

The title compounds, [Fe(C₅H₅)(C₁₄H₁₃O₂)] and [Fe(C₅H₅)(C₁₅H₁₅O₂)], respectively, contain the ferrocenyl η⁵(C₅H₄) and phenyl­ene –C₆H₄– rings in a nearly coplanar arrangement, with interplanar angles of 6.88 (12) and 10.5 (2)°, respectively. Molecules of the ethyl ester form dimers through η⁵(C₅H₅)C—H⋯O=C hydrogen bonds, with graph set R(20), and, together with Csp³—H⋯π(C₅H₅) interactions, generate a one‐dimensional column (irregular ladder). Molecules of the iso­propyl ester aggregate through η⁵(C₅H₅)C—H⋯π(C₆H₄) interactions.     

Concise, enantiospecific synthesis of (3S,4R)-3-amino-4-ethylpiperidine as partner to a non-fluoroquinolone nucleus

An enantiospecific, eight-step synthesis of (3S,4R)-3-amino-4-ethylpiperidine 3 starting from readily available (S)-(−)-α-methyl-4-pyridinemethanol 6 has been achieved utilizing an Overman rearrangement of a chiral allylic trichloroacetimidate 13 as the key step. A diastereoselective hydrogenation of the resulting chiral allylic amine 15 afforded predominantly the desired trans-substituted piperidine. The conformation of the piperidine along with the directing nature of the amino function are implicated in the selectivity observed.