Stereoselective and Regioselective Pinacol‐Type Rearrangement of a Fused Bicyclic Oxetanol Scaffold

Abstract

The Paternò‐Büchi reaction between benzaldehyde and trimethylsilyloxycyclopentene gave access to an unprecedented silyl ether derivative of 6‐oxabicyclo[3.2.0]heptan‐1‐ol. The bicyclic structure underwent selective reductive ring opening and acid‐catalyzed pinacol‐type rearrangement reactions with complete regioselectivity, accompanied by moderate to excellent mechanism‐dependent diastereoselectivity.

Boron Trifluoride-Mediated Cycloaddition of 3-Bromotetrazine and Silyl Enol Ethers: Synthesis of 3-Bromo-pyridazines

“…1 H NMR (CDCl 3 , 400 MHz) δ 4.62–4.61 (m, 1H), 2.29–2.23 (m, 4H), 1.89–1.82 (m, 2H), 0.21 (s, 9H). The obtained analytical data are consistent with the values reported in the literature …”

Oxetanes and Oxetenes: Fused-Ring Derivatives

“…Photoadduct 56, arising from a Paternò-Büchi reaction between benzaldehyde and trimethylsilyloxycyclopentene, was found to undergo clean reduction to the corresponding tertiary alcohol 57 or a regioselective rearrangement to cyclohexanone 58 via an aluminum(III)-mediated pinacol type process. 75 <Scheme 17 near here> One step reduction of b-lactones 59 to oxetanes 60 has not been reported in the literature, which prompted the development of a 2-step sequence implying reduction to the diol followed by cyclization under basic conditions. 76 The first step of the process turned out to be quite difficult, leading to decomposition via retro-aldol reactions.…”

RuPHOX-Ru-Catalyzed Selective Asymmetric Hydrogenation of Exocyclic α,β-Unsaturated Pentanones

“…(1R,2R)-1-Benzylcyclopentane-1,2-diol (5). 20 A hydrogenation tube was charged with a stirring bar, 4 (0.9 mmol, 190.2 mg), and Pd/ C (10 mol %), followed by the addition of THF/MeOH (10 mL/5 mL) using a syringe. The hydrogenation tube was then put into an autoclave.…”