Generation of Benzyne Species from Diphenylphosphoryl Derivatives: Simultaneous Exchange of Three Functional Groups.

Interaction of (2-diphenylphosphoryl-3-iodo-4-methoxy-phenyl) methanol with NaH in DMF at ambient temperature results in the generation of benzyne intermediates that can be trapped by furan or DMF. Trapping with DMF forms 3-(dimethylaminomethyl)-2-hydroxy-6-methoxybenzaldehyde demonstrating the simultaneous exchange of three functionalities in a single step. The presence of the alkoxy substituent adjacent to iodine is critical for high regioselectivity addition of DMF.

Synthesis and comparative characterization of 9-boraanthracene, 5-boranaphthacene, and 6-borapentacene stabilized by the H2IMes carbene.

A general procedure for the preparation of three N-heterocyclic carbene stabilized, boron-containing acenes (9-boraanthracene, 5-boranaphthacene, and 6-borapentacene) is presented. The key steps involve a transmetallation reaction between BCl(3) and an appropriate stannacyclic precursor, and the dehydrochlorination of the H(2)IMes adduct of the chloroborane product. Comparative structural, photophysical, and redox properties reveal narrow HOMO-LUMO gaps relative to the all-carbon acene analogues.

Spirocyclic boronium ions: precursors to persistent neutral radicals.

Spirocyclic boronium ions based on the 9-bora-9,10-dihydroanthracene scaffold and substituted 2,2'-bipyridyl ligands have been prepared; these cations are shown to be convenient starting materials for the preparation of neutral radicals with significant spin density on boron.

Diastereoselective Diels-Alder reactions with an allenyl-containing spiro-amido chiral auxiliary.

A novel allenyl-containing 1,3-spiro-amido alcohol auxiliary has been prepared and used in a variety of diastereoselective Diels-Alder reactions providing exclusively endo adducts with diastereomeric ratios ranging from 2:1 to >99:1.

A concise Diels-Alder strategy for the asymmetric synthesis of (+)-albicanol, (+)-albicanyl acetate, (+)-dihydrodrimenin, and (-)-dihydroisodrimeninol.

A short, mild, highly diastereo-, regio-, and stereoselective Diels-Alder strategy has been developed for the asymmetric synthesis of (+)-albicanol, (+)-albicanyl acetate, (+)-dihydrodrimenin, and (-)-dihydroisodrimeninol.

9-Boraanthracene derivatives stabilized by N-heterocyclic carbenes.

2009: A boraanthracene odyssey: General routes to boraanthracene derivatives--long proposed, but never observed--are disclosed, along with the structural and photophysical properties of these compounds and their remarkable reactivity towards oxygen.

Diastereoselective Diels-Alder reactions of a novel cyclopropenyl-containing chiral auxiliary.

A novel cyclopropenyl-containing 1,3-spiroaminoalcohol auxiliary has been used in a variety of asymmetric Diels-Alder reactions providing endo adducts with diastereomeric ratios ranging from 2:1 up to >99:1. In addition, unexpected regiochemistry was observed for a Diels-Alder reaction between cyclopropenyl dienophile and 4-vinyl-1,2-dihydronapthalene.

Use of deuterium labeling studies to determine the stereochemical outcome of palladium migrations during an asymmetric intermolecular Heck reaction.

A series of deuterium labeling experiments showed that Pd migrations during an intermolecular asymmetric Heck reaction between phenyl triflate and various deuterated 2,3-dihydrofurans (2b, 2c, 2d, 2e) occurs exclusively by either syn-1,2-dyotropic shifts or a syn-chain-walking mechanism; no evidence was observed to support anti-1,2-dyotropic shifts or anti-beta-H Pd eliminations during the formation of 6 and 7.

1-Borabarrelene derivatives via Diels-Alder additions to borabenzenes.

[reaction: see text] Borabenzene reacts with strong dienophiles such as dimethylacetylenedicarboxylate or benzyne to afford substituted borabarrelenes and borabenzobarrelene, respectively. The resultant Diels-Alder adducts display high stability due to increased Lewis acidity at boron.

3,3'-disubstituted BINAP ligands: synthesis, resolution, and applications in asymmetric hydrogenation.

A novel family of BINAP ligands were prepared with alkoxy- and acetoxy-derived substituents in the 3,3'-positions. They were prepared through a convergent synthesis starting from readily available 4-bromo-2-naphthol. These ligands afforded excellent enantioselectivities in the asymmetric hydrogenation of substituted olefins.

Enantiocomplementary enzymatic resolution of the chiral auxiliary: cis,cis-6-(2,2-dimethylpropanamido)spiro[4.4]nonan-1-ol and the molecular basis for the high enantioselectivity of subtilisin Carlsberg.

cis,cis-(+/-)-6-(2,2-Dimethylpropanamido)spiro[4.4]nonan-1-ol, 1, a chiral auxiliary for Diels-Alder additions, was resolved by enzyme-catalyzed hydrolysis of the corresponding butyrate and acrylate esters. Subtilisin Carlsberg protease and bovine cholesterol esterase both showed high enantioselectivity in this process, but favored opposite enantiomers.

Why Do Catalytic Quantities of Lewis Acid Generally Yield More Product than 1.1 Equiv in the Intramolecular Diels-Alder Reaction with a Furan Diene? 2.(1) AM1 Calculations and Mathematical Simulation of the Equilibria.

The results presented here provide additional support for our hypothesis based on the relative basicity of the reaction controlling functional group to rationalize experimental observations on intramolecular Diels-Alder reactions with a furan diene (IMDAF) regarding the quantity (0.1 or 1.1 equiv) of Lewis acid required to facilitate the reaction most effectively.