α-Tetrasubstituted Aldehydes through Electronic and Strain-Controlled Branch-Selective Stereoselective Hydroformylation
作者:Josephine Eshon、Floriana Foarta、Clark R. Landis、Jennifer M. Schomaker
DOI:10.1021/acs.joc.8b01431
日期:2018.9.7
high conversions and yields of tetrasubstituted aldehydes (e.g., 13:1 regioselectivity, 85% ee, and <1% hydrogenation for 1-fluoromethyl acrylate). The scope also encompasses both acyclic 1,1′-disubstituted and trisubstituted, electron-poor alkenes as well as di- and trisubstituted alkenes composed of small rings with exocyclic and endocyclic unsaturation. For example, 1-methylene-β-lactam furnished
Pd/C-catalyzed hydrogenationreaction of 2-methylenecyclobutanones (2-MCBones) occurs at their exocyclic CC sites regio-specifically to produce 2-substituted cyclobutanones, which are useful building blocks for the synthesis of drug and pesticide intermediates and are key intermediates in the total synthesis of many natural products. Surprisingly, atmospheric pressure H2 in balloon can be used as the
A Novel Route to Geminal Dibromocyclobutanes: Syntheses of 2-Substituted Cyclobutanone Acetals and Their Reaction with Boron Tribromide
作者:Tore Nordvik、Udo H. Brinker
DOI:10.1021/jo035295o
日期:2003.11.1
Nine 2-substituted cyclobutanone acetals, in addition to the parent cyclobutanone acetal, were synthesized from their corresponding cyclobutanones and subsequently treated with boron tribromide. The substituents were either alkyl chains or a phenyl and a benzyl group, respectively. The major compounds obtained in these reactions were, in most cases, the geminal dibromocyclobutanes which were obtained
generated in the α-position of various ketones viasynthesis of enaminone (step 1) and treatment with organomagnesium (step 2) with subsequent catalytic hydrogenation (step 3, 1° alkyl) or organocopperreagents (step 4, 2° alkyl). Tolerance toward ester, Boc-protected amine, and α-fluoro-substituted ketone moieties was demonstrated. The suitability of the method for late-stage natural product modification