Competing Mechanisms in Palladium-Catalyzed Alkoxycarbonylation of Styrene

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61388963%3A_____%2F24%3A00585169" target="_blank" >RIV/61388963:_____/24:00585169 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/00216208:11310/24:10483701

Výsledek na webu

<a href="https://doi.org/10.1021/acscatal.4c00966" target="_blank" >https://doi.org/10.1021/acscatal.4c00966</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1021/acscatal.4c00966" target="_blank" >10.1021/acscatal.4c00966</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Competing Mechanisms in Palladium-Catalyzed Alkoxycarbonylation of Styrene

Popis výsledku v původním jazyce

Palladium-catalyzed carbonylation is a versatile method for the synthesis of various aldehydes, esters, lactones, or lactams. Alkoxycarbonylation of alkenes with carbon monoxide and alcohol produces either saturated or unsaturated esters as a result of two distinct catalytic cycles. The existing literature presents an inconsistent account of the procedures favoring oxidative carbonylation products. In this study, we have monitored the intermediates featured in both catalytic cycles of the methoxycarbonylation of styrene PhCH & boxH, CH2 as a model substrate, including all short-lived intermediates, using mass spectrometry. Comparing the reaction kinetics of the intermediates in both cycles in the same reaction mixture shows that the reaction proceeding via alkoxy intermediate [Pd-II]-OR, which gives rise to the unsaturated product PhCH & boxH, CHCO2Me, is faster. However, with an advancing reaction time, the gradually changing reaction conditions begin to favor the catalytic cycle dominated by palladium hydride [Pd-II]-H and alkyl intermediates, affording the saturated products PhCH2CH2CO2Me and PhCH(CO2Me)CH3 preferentially. The role of the oxidant proved to be crucial: using p-benzoquinone results in a gradual decrease of the pH during the reaction, swaying the system from oxidative conditions toward the palladium hydride cycle. By contrast, copper(II) acetate as an oxidant guards the pH within the 5-7 range and facilitates the formation of the alkoxy palladium complex [Pd-II]-OR, which favors the oxidative reaction producing PhCH & boxH,CHCO2Me with high selectivity. Hence, it is the oxidant, rather than the catalyst, that controls the reaction outcome by a mechanistic switch. Unraveling these principles broadens the scope for developing alkoxycarbonylation reactions and their application in organic synthesis.

Název v anglickém jazyce

Competing Mechanisms in Palladium-Catalyzed Alkoxycarbonylation of Styrene

Popis výsledku anglicky

Palladium-catalyzed carbonylation is a versatile method for the synthesis of various aldehydes, esters, lactones, or lactams. Alkoxycarbonylation of alkenes with carbon monoxide and alcohol produces either saturated or unsaturated esters as a result of two distinct catalytic cycles. The existing literature presents an inconsistent account of the procedures favoring oxidative carbonylation products. In this study, we have monitored the intermediates featured in both catalytic cycles of the methoxycarbonylation of styrene PhCH & boxH, CH2 as a model substrate, including all short-lived intermediates, using mass spectrometry. Comparing the reaction kinetics of the intermediates in both cycles in the same reaction mixture shows that the reaction proceeding via alkoxy intermediate [Pd-II]-OR, which gives rise to the unsaturated product PhCH & boxH, CHCO2Me, is faster. However, with an advancing reaction time, the gradually changing reaction conditions begin to favor the catalytic cycle dominated by palladium hydride [Pd-II]-H and alkyl intermediates, affording the saturated products PhCH2CH2CO2Me and PhCH(CO2Me)CH3 preferentially. The role of the oxidant proved to be crucial: using p-benzoquinone results in a gradual decrease of the pH during the reaction, swaying the system from oxidative conditions toward the palladium hydride cycle. By contrast, copper(II) acetate as an oxidant guards the pH within the 5-7 range and facilitates the formation of the alkoxy palladium complex [Pd-II]-OR, which favors the oxidative reaction producing PhCH & boxH,CHCO2Me with high selectivity. Hence, it is the oxidant, rather than the catalyst, that controls the reaction outcome by a mechanistic switch. Unraveling these principles broadens the scope for developing alkoxycarbonylation reactions and their application in organic synthesis.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10401 - Organic chemistry

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2024

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

ACS Catalysis

ISSN

2155-5435

e-ISSN

2155-5435

Svazek periodika

14

Číslo periodika v rámci svazku

8

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

10

Strana od-do

5710-5719

Kód UT WoS článku

001194996300001

EID výsledku v databázi Scopus

2-s2.0-85189558674