Spiroannelation of Enol Silanes: 2‐Oxo‐5‐Methoxysplro[5.4]Decane

Abstract

Spiroannelation of enol silanes: 2‐oxo‐5‐methoxysplro[5.4]decane intermediate: 1‐bromo‐3,3‐dimethoxypropane solvent: petroleum ether (10 mL) intermediate: 1‐trimethylstannyl‐3,3‐dimethoxypropane reactant: trimethylsilyl trifluoromethanesulfonate (1.47 g; 6.6 mmol) catalyst: titanium tetrachloride (7.40 g, 39.0 mmol) in dichloromethane (10 mL) product: 2‐oxo‐5‐methoxyspiro[5.4]decane reactant: Cyclohexane carboxaldehyde was obtained from the Aldrich Chemical Company, Inc.

Asymmetric Synthesis of Polyfunctionalized Mono‐, Bi‐, and Tricyclic Carbon Frameworks via Organocatalytic Domino Reactions

“…In the first step the ozonolysis in DCM/MeOH followed by a reductive work-up provided the monoprotected dialdehyde 24 in 81 % yield. [17] Subsequent Henry reaction [18] and dehydration [19] of the intermediate nitro alcohol gave the nitroalkene aldehyde 25 after acidic cleavage of the acetal moiety. Although the reaction was slow (four days) due to the lower reactivity of the aliphatic nitroalkene, we were able to isolate the domino product 26 after chromatography in diastereomerically pure form (21 %) and with an enantiomeric excess of 79 %.…”