Synthesis of Coumarins via Pd-Catalyzed Oxidative Cyclocarbonylation of 2-Vinylphenols

Abstract

Palladium-catalyzed oxidative cyclocarbonylation of 2-vinylphenols constitutes a simple, direct method for the synthesis of coumarins. The reaction conditions, employing low pressures of CO, and air or 1,4- benzoquinone as the oxidant, are attractive in terms of environmental considerations and operational simplicity. Coumarins with a variety of functional groups were prepared in yields up to 85%.

Cp*Co(III)-Catalyzed Annulations of 2-Alkenylphenols with CO: Mild Access to Coumarin Derivatives

“…For example, Alper reported a Pd(II)-catalyzed oxidative cyclocarbonylation of 2-vinyphenols, with a relatively high pressure of CO applied (Scheme 1a). 21 Iwasawa disclosed an elegant Pd-catalyzed direct carboxylation of alkenyl C−H bonds with CO 2 , which lead to a redox-neutral access to coumarins (Scheme 1b). 22 Mascarenãs and Gulías realized a Cp*Rh(III)-catalyzed carbonylation of o-alkenyl phenols with CO, wherein a relatively high temperature was used (Scheme 1c).…”

A General Palladium‐Catalyzed Carbonylative Synthesis of Chromenones from Salicylic Aldehydes and Benzyl Chlorides

“…Our interest in heterocycle synthesis prompted us to apply carbonylation to chromenone preparation. In the previous literature, Larock and Kadnikov reported a procedure starting from internal alkynes and 2‐iodophenols8 and Alper and co‐workers developed the oxidative cyclocarbonylation of 2‐vinylphenols (Scheme ) 9. As our experience is with the carbonylation of benzyl chlorides and the study of coumarins,10 we wish to report here a straightforward procedure for the carbonylation of salicylic aldehydes and benzyl chlorides to form coumarins.…”

“…In the previous literature, Larock and Kadnikov reported a procedure starting from internal alkynes and 2-iodophenols [8] and Alper and co-workers developed the oxidative cyclocarbonylation of 2-vinylphenols (Scheme 2). [9] As our experience is with the carbonylation of benzyl chlorides and the study of coumarins, [10] we wish to report here a straightforward procedure for the carbonylation of salicylic aldehydes and benzyl chlorides to form coumarins. Notably, the substrates and chemicals applied herein are stable and commercially available, which highlights the synthetic importance of this method.…”

Synthesis and biological evaluation of thiophosphate tricyclic coumarin derivatives as steroid sulfatase inhibitors

“…Many convenient synthetic methods have been described, including Pechmann [7], Perkin [8], Knoevenagel condensation [9], Reformatsky [10], and Wittig reactions [11]. Recent reports of the synthesis of coumarin derivatives include the use of metal triflates in qFriedel-Crafts alkenylations of aromatic compounds with various alkyl-and aryl-substituted alkynes [12], hydroarylation of arylpropionic acid methyl esters having a methoxymethyl acetal (MOM) protected hydroxy group with various arylboronic acids in the presence of a catalytic amount of CuOAc [13], reaction of substituted phenyl acetic acids and substituted 2-hydroxy benzaldehydes in the presence of cyanuric chloride (2,4,6-trichloro-1,3, 5-triazine) and N-methyl morpholine [14], palladium-catalyzed oxidative cyclocarbonylation of 2-vinylphenols [15], condensation of aroylketene dithioacetals, and 2-hydroxybenzaldehydes in the presence of a catalytic amount of piperidine [16], or reaction of 2-hydroxybenzaldehydes, triphenylphosphine, and dialkyl acetylenedicarboxylate via vinyltriphenylphosphonium salt-mediated aromatic electrophilic substitution [17].…”