Jeffery B. Press

Regiospecific Synthesis of Unsymmetrical α-Bromoketones

Abstract A convenient regiospecific preparation of unsymmetrical α-bromoketones, commencing from Meldrums acid, has been developed. This procedure allows for preparation of α-bromoketones which are unobtainable in a pure state by other bromination methods and is compatable with introduction of a bromine atom in the presence of unsaturation using low-cost starting materials.

Deethylation of Aryl Ethyl Ethers by Boron Tribromide

Abstract Boron tribromide is well known as an effective reagent for cleaving methyl aryl ethers.1,2 This procedure suffers from the unpredictable variability in the yield of the phenolic products arising from this cleavage.lb While not reported as a preparative procedure, Egly et al.3 note that boron tribromide cleaves linear alkyl (up to chain length C10) aryl ethers to yield, among a mixture of products, phenols, albeit in low yield.

Synthesis of 4-Hydroxy-1H-indole-2-carbonitrile via a Vinylnitrene Cyclization

Abstract Literature methods to prepare 1 failed and a reaction sequence was developed to prepare 4-hydroxy-1H-indole-2-carbonitrile (1) by means of an azide decomposition to form the indole ring. The 2-cyano functionality could not be introduced directly but was derived by functionalization of an ester.

Trimethylsilylazide/KN3/18-Crown-6. Formation and Curtius Rearrangement of Acyl Azides from Unreactive Acid Chlorides

Abstract Trimethylsilylazide (TMSA) has been reported as a safe, stable substitute for hydrazoic acid in the preparation of acyl azides from acid anhydrides and chlorides.1 Subsequent thermolysis of these acyl azides in situ has yielded isocyanates via the Curtius rearrangement.1,2

4H-1,4-benzothiazine derivatives via a novel lead tetraacetate induced ring contraction.

Abstract 8-Chloro-3,4-dihydro-5-(2-thienyl)-2H-1,6-benzothiazocine underwent a facile lead tetraacetate induced ring contraction forming several 3-(2-thienyl)-4H-1,4-benzothiazine derivatives.

A Practical Synthesis of ω-Aminoalkanoic Acid Derivatives from Cycloalkanones

Abstract A practical synthetic route to N-Boc protected or Boc-amino acid coupled ω-aminoalkanoic acids is reported and exemplified by the preparation of 8-(t-butoxycarbonylamino)caprylic acid 2 and (N-t-butoxycarbonylphenylalanyl)-8-aminocaprylic acid 3. The sequence does not involve column chromatography, hydrogenation, azide or bromine related rearrangements, and therefore is amenable to scale-up. Homologues of the ω-aminoalkanoic acid derivatives may also be prepared by using different cycloalkanones.

An Unusual Aminal Derivative from a Misdirected Gabriel Synthesis

Abstract N-(2-Bromoethyl)phthalimide (1) was reacted with sodium imidazolate in DMF to give the novel aminal N-[1-(1H-imidazol-1-yl)ethyl]phthalimide (4a) as well as N-vinylphthalimide (3) and the desired Gabriel intermediate 2. Aminal 4a as well as heterologues 4b - d form directly from reaction of 3 with the appropriate heterocyclic sodium salt.

Carbathia analogues of platelet activating factor (PAF)

Abstract Sulfur analogues of “2-carba” PAF, 1a and 1b, were prepared by an 8-step synthesis using commercially available ethyl levulinate as a starting material.