Dual Platinum and Pyrrolidine Catalysis in the Direct Alkylation of Allylic Alcohols: Selective Synthesis of Monoallylation Products

Abstract

A dual platinum- and pyrrolidine-catalyzed direct allylic alkylation of allylic alcohols with various active methylene compounds to produce products with high monoallylation selectivity was developed. The use of pyrrolidine and acetic acid was essential, not only for preventing undesirable side reactions, but also for obtaining high monoallylation selectivity.

Transition metal-catalyzed allylic substitution reactions with unactivated allylic substrates

“…63 Additionally, direct reaction of a mixture of 39 and a catalytic amount of 40 and acetic acid also produced identical results. The result was identical to that of the reaction between b-keto ester 39 in the presence of catalytic amounts of pyrrolidine and acetic acid.…”

“…Le Floch and co-workers proposed that ligands with a large bite-angle prevent the formation of platinum hydride complexes and therefore the formation of an inactive bicyclic aminopropyl complex. 63 Direct alkylation of a number of 1,3-diketone products was successful using a [Pt(cod)Cl 2 ] catalyst precursor in the presence of Xantphos ligand L15 in DMF solvent. Interestingly, electronic effects of the ligand do not play a significant role in Oshima and co-workers improved the reaction selectivity and reduced the formation of unwanted by-products by adding a catalytic amount of pyrrolidine and acetic acid to the reaction mixture (Table 12).…”

A Mixed‐Ligand Chiral Rhodium(II) Catalyst Enables the Enantioselective Total Synthesis of Piperarborenine B

“…In the most time and scale efficient route (Scheme 3), veratraldehyde was treated with vinylMgBr to provide a vinyl alcohol that was shown to be an effective substrate for an ‘on water’ Tsuji-Trost allylation of tert -butyl acetoacetate using Pd(OAc) 2 (2 mol %), PPh 3 (10 mol %), and adamantoic acid (10 mol %). [24] Treatment of ketoester 2 with p- ABSA, and NaOH in a mixture of acetonitrile/H 2 O provided the desired diazoester 3 in 47% yield over three steps. This three step process for diazoester synthesis was accomplished in one day and represents an efficient new strategy for α-allyl-α-diazoester synthesis.…”

A d‐Camphor‐Based Schiff Base as a Highly Efficient N,P Ligand for Enantioselective Palladium‐Catalyzed Allylic Substitutions

“…[3] Moreover,c hiral li-gands bearing phosphorus and nitrogen atoms are widely used in transition-metal-catalyzed asymmetric syntheses. [4] Notably,d espite impressive and extensive advances in this field, the development of highly efficient, readily accessible, and structurally novel chiral N,P ligands to meet the demando f perfect enantioselective transformations with potentiali ndustrial value remains aformidablec hallenge. [5] This has motivated researchers to develop new andp ractical approaches to establish structurally simple backbones fort he modulation of chiral N,P ligands.…”