Diastereoselective 1,4-addition of various nucleophiles to 5-trimethylsilyl-2-cyclohexenone: synthesis of (+)-ramulosin

A Strategy for the Convergent and Stereoselective Assembly of Polycyclic Molecules

“…The choice of these particular enones was predicated on a combination of their accessibility in optically pure form (where appropriate), their commercial availability or ease of synthesis, and because the products formed after oxidative coupling and ring-closure mapped onto substructures of interest to us. ( R )- and ( S )-carvone [( R )- 7 and ( S )- 7 ] and methylvinylketone ( 12 ) are commercially available, while compounds 1 – 6 were prepared in 99% ee from (5 R )-trimethylsilylcyclohexenone as a readily available chiral synthon. − Compounds 8 , and 9 could be easily made from ( R )- or ( S )-carvone, respectively. Enone 10 could be produced from commercially available (−)-quinnic acid, and a simple allylation of cyclohexenone delivered enone 11 .…”

Fragmentverknüpfungen in der Totalsynthese – Bildung von C‐C‐Bindungen über intermediäre Carbanionen oder freie Radikale

“…Außerdem berichteten Mander und Fairweather [155a] sowie Shenvi et al [155b] [156] Durch diastereoselektive konjugierte Addition von Isopropenylmagnesiumbromid und oxidative Eli-minierung des Tr imethylsilylsubstituenten mit CuCl 2 wurde das Enon 269 erhalten. [157] [108a, 125] Ausd iesem Dion ist (+ +)-7,20-Diisocyanoadocian (265) über eine von Corey und Magriotis entwickelte,d reistufige Reaktionssequenz zugänglich. [153] Zusammenfassung und strategische Lektionen: (À)-Chromodorolid B( 284)i st ein umgelagertes Spongian-Diterpen, das zuerst aus Nacktkiemern der Gattung Chromodoris isoliert wurde.…”

2-Pyrrolidinones and 3-Pyrrolin-2-ones: A Study on the Chemical Reactivity of These Structural Moieties

“…We planned to use compound 18 as substrate for accomplishment of that conjugate addition reaction with other nucleophiles, based on previous experiments reported in the literature. Thus, the addition of amines [15] and malonate anion [16] to α,β-unsaturated system of 18 was evaluated. The results from these addition reactions are displayed in Table 3 with the respective products analysed by NMR.…”