DoE (Design of Experiments) Assisted Allylic Hydroxylation of Enones Catalysed by a Copper–Aluminium Mixed Oxide

Abstract

The allylic hydroxylation of enones using dioxygen as the oxidant has been studied. The reaction was first examined in the absence of any catalyst, using β-ionone as a model substrate. Then a new copper-aluminium mixed oxide, Cu-Al Ox, was prepared and characterized in order to be used as a catalyst. This oxide showed good activity, and provided the corresponding γor ε-hydroxylated enones, starting from different α,βor α,β,γ,δ-unsaturated ketones. In all cases, the [a]

Fused‐Ring Formation by an Intramolecular “Cut‐and‐Sew” Reaction between Cyclobutanones and Alkynes

“…Tr eatment of product 2a with base and hydrogen peroxide unexpectedly led to a ghydroxylation product (7). [14] Finally,i odine/dimethyl sulfoxide (DMSO) oxidation [15] converted the tricycle into af unctionalized fluorene,a nd aP d-catalyzed aerobic oxidation [16] surprisingly gave 9-fluorenone 9 as the dominant product.…”

Total Synthesis of (+)‐Sarcophytin

“…[7] On the other hand, in our retrosynthetic analysis akey issue to be examined was whether transposition of the C(10) À C(11) double bond in 6 could be employed as ah andle for hydroxylation of C(10) while at the same time generating the unsaturated ester 5.T etracycle 6 suggests aDiels-Alder cycloaddition reaction of ester 7,which may be readily disconnected into two fragments (Scheme 1B)o f similar complexity,l eading to ah ighly convergent approach. [9,10] Thec ycloaddition involving tethered electron-deficient reaction partners,n amely an enone and ad ienoate as shown for 7,s ets up as ituation with little precedence. [11] The configuration at C(14) would be critical for facial selectivity in the cycloaddition of 7,controlling the C(4), C(5) and C(13) stereocenters,p rovided the Diels-Alder reaction proceeded through an exo transition state.…”

“…With ar oute to dienes 15 and 18 in hand and hydroxyenone 9 readily available, [9,10] as tudy of the Diels-Alder reaction was conducted on (E,anti)-19 and (Z,anti)-19,which possess the (1R)configuration (Scheme 3) identical to that at C(1) in target 4. [19] Unfortunately,n oc ycloaddition occurred upon heating (E,anti)-19 in DMSO at 150 8 8C, decomposition was observed and at higher temperatures.B ycontrast, when (Z,anti)-19 was heated to 100 8 8C, rapid intramolecular Diels-Alder was observed in 53 %y ield to give (1R,12S)-20.T he excitement over this promising result, however,w as dampened by the outcome of the esterification of 18 with ent-9, affording (Z,anti)-19 in low yield and (E,anti)-19 as side product.…”

Total Syntheses of (+)‐Sarcophytin, (+)‐Chatancin, (−)‐3‐Oxochatancin, and (−)‐Pavidolide B: A Divergent Approach

“…Guided by our biosynthetic hypothesis for 5,acrucial pinacol rearrangement [7] of the cis-diol 8 was projected as the means to forge the [6,5,7] tricyclic carbon framework of this natural product. [10] Finally,t he preparation of 11 could be traced back to the readily available chiral alcohol (À)-12 [6,11] and Rawal diene 13 [12] by taking advantage of ad ouble Mukaiyama Michael addition/elimination process. [9] The latter compound in turn should be accessible from the bicyclic enone 10 and Grignard reagent 11 through aH elquist annulation.…”

“…[9] The latter compound in turn should be accessible from the bicyclic enone 10 and Grignard reagent 11 through aH elquist annulation. [10] Finally,t he preparation of 11 could be traced back to the readily available chiral alcohol (À)-12 [6,11] and Rawal diene 13 [12] by taking advantage of ad ouble Mukaiyama Michael addition/elimination process. [13] Our synthesis began with construction of the common intermediate 9 (Scheme 2).…”