Microwave Induced Rate Enhancement in Aldol Condensation

Enantioselective Synthesis of 4‐Desmethyl‐3α‐hydroxy‐15‐rippertene

“…[20] Annelation of the five-membered ring was accomplished by a short sequence including a diastereoselective allylation [21] to provide 12, a Wacker oxidation under modified conditions, [22] and an additional aldol cyclization under microwave irradiation to generate 13. [23] Dienone 13 contained four of the seven stereogenic centers needed for 1 and 2; the configuration was unambiguously confirmed by X-ray diffraction analysis. [24] Construction of the tetracyclic rippertene core was achieved by an efficient intramolecular Diels-Alder reaction from the cyclization precursor 14, which was made by the diastereoselective reduction of 13 and subsequent etherification using propargyl bromide.…”

Ruthenium‐Catalyzed, Keto‐Directed, Site‐Selective C–H Activation of Diverse Chromanones with Alkenes

“…Flavones are key structural skeletons and are widely dispersed as plant pigments that are yellow in color; they exist either in the form of glycosides linked with tannins or in the free state . They exhibit various biological activities, including antifungal, antimutagenic, and anti‐inflammatory activities, in medicinal chemistry and are an integral part of many naturally occurring compounds (Figure ) …”

Novel and Efficient One Pot Condensation Reactions between Ketones and Aromatic Alcohols in the Presence of CrO3 Producing α,β‐Unsaturated Carbonyl Compounds

“…For examples, it was reported that microwave irradiation enhanced benzaldehyde/acetone condensation, and produced 80% benzalacetone using aqueous NaOH as a catalyst. 8 The yield of the same condensation reaction catalyzed by ionic liquids 2-HEAP is 86%. 9 In these two cases, the yields are similar to that obtained in the present study for benzalacetone via the benzyl alcohol/acetone condensation (which is 86%, Entry 2 in Table 1).…”