Raymond J. Giguere

Diastereoselectivity and regiocontrol in intramolecular allyl cation cycloadditions: Selective formation of [3 + 2] or [3 + 4] cycloadducts.

Abstract Intramolecular Hoffmann-Noyori reactions of chiral, diastereomeric trienols 1a and 1b demonstrate site-selectivity control to form either [3+4] or [3+2] cycloadducts 2a and 2b , respectively. Furthermore, both reactions exhibit a high degree of diastereoselectivity. Cycloaddition precursors 1a,b are prepared from (−)-S-citronellol in 33% overall yield.

Microwave Heating in Organic Synthesis: Decarboxylation of Malonic Acid Derivatives in Water

Abstract Microwave heating permits rapid decarboxylation (15 min, 80–98% isolated yields) of malonic acids in water when employing a microwave autoclave mode and high reaction temperature and power (190°C; 800 Watts).

Microwave Heating in Synthesis: Preparation of Allyldiphenylphosphine Oxide

Abstract A new one-pot synthesis of allyldiphenyl-phosphine oxide has been developed using a tandem Sn2′ / Michaelis-Arbuzov sequence. The application of microwave heating lowers the reaction time significantly.

The tandem intramolecular Diels-Alder reaction

Abstract The tandem intramolecular Diels-Alder (TIMDA) reaction of ketone 3 is reported. The reaction proceeds under mild conditions (BF 3 ·Et 2 O, O °C) and affords two tetracyclic products diastereoselectively. TIMDA substrate 3 is prepared in a convergent manner from 1,5-pentanediol.

Tandem Intramolecular Diels-Alder (Timda) Reactions: Branched Substrate Studies and New Synthetic Pathways

Abstract Using a malonic ester route, the first branched tandem intramolecular Diels-Alder (TIMDA) precursor, 3, was synthesized from sorbic acid in seven steps (15% overall yield). Treatment with Lewis acid catalysts (e.g., boron trifluoride etherate) affects the TIMDA reaction to afford a new fused-tetracyclic, 4, as two diastereomers (1:1). An alternative synthetic route to key intermediates used in the synthesis of linear TIMDA precursors has also been achieved.

Oxygenated limonene analogs. Preparation of tetramethylated carvone and carveols via regiocontrolled opening of tetramethyllimonene oxide.

Abstract Regioselective opening of trans epoxide 2 gave endo and exo tetramethylated trans carveols 3t and 4t respectively, which were oxidized to tetramethylcarvone ( 5 ) and its unstable exocylic isomer 6 ; reduction of 5 with DIBAH gave tetramethylated cis carveol 3c exclusively, whilst analogus reduction of 6 produced an epimeric mixture of 4c : 4t =85:15.

Synthetic Application of the Alder-Bong Reaction: Stereoselective Construction of the Methanohydroazulene Framework

Abstract Tandem ene/intramolecular Diels-Alder reaction of ketal 1 and DMAD permits direct entry to strained pentacyclic adducts 2a, b in high yield. Acid-catalysed deprotection and subsequent fragmentation of adduct 2a with BF3.Et2O in dichloromethane stereoselectively affords methanohydroazulene 3.