Ligand-Enabled C6-Selective C-H Arylation of Pyrrolo[2,3-d] Pyrimidine Derivatives with Pd Catalysts: An Approach to the Synthesis of EGFR Inhibitor AEE-788

Herein, we report the Pd(II)-catalyzed direct C-H arylation of pyrrolo[2,3-d]pyrimidine derivatives with aryl iodides, which is enabled by bidentate pyridine-pyridine ligands. A range of aryl iodides proved to be suitable coupling partners affording the desired products in good yields with high levels of C6 selectivity. This protocol features good tolerance of reactive functional groups, mild reaction conditions, and a simple reaction system, which provides an expeditious route to an essential class of 6-arylpyrrolo[2,3-d]pyrimidines frequently found in bioactive compounds, and provides a step-economical access to the second-generation EGFR inhibitor AEE-788.

Visible-Light-Induced Highly Site-Selective Direct C-H Phosphorylation of Pyrrolo[2,3-d]pyrimidine Derivatives with H-Phosphine Oxides

An efficient and highly regioselective C6-phosphorylation protocol for pyrrolo[2,3-d]pyrimidine (7-DAP) derivatives with various H-phosphine oxides induced by visible light at room temperature is described for the first time. This protocol has been successfully achieved by the combination of Na2-eosin Y as a photocatalyst and LPO as an oxidant under transition metal- and additive-free conditions. The broad substrate scope, good functional group tolerance, excellent regioselectivity, and air tolerant conditions make this process favorable for the functional modification of pyrrolo[2,3-d]pyrimidine scaffold and enrich the phosphorylated 7-DAP compounds for further biological evaluation.

Ruthenium-catalysed direct C-H amidation of 4-aryl-pyrrolo[2,3-d]pyrimidines with acyl/phosphoryl azides

A ruthenium-catalysed arene ortho C-H amidation of 4-aryl-pyrrolo[2,3-d]pyrimidine derivatives with acyl azides or phosphoryl azides as the nitrogen sources toward C-N bond formation was developed. This protocol could offer a novel and direct approach to access a series of amidated and phosphoramidated pyrrolo[2,3-d]pyrimidine derivatives in moderate to good yields, thereby evading the general Curtius rearrangement. The protocol features significant functional group tolerance and a single-step process, with the release of only innocuous molecular nitrogen as the byproduct.

Palladium-catalysed site-selective arene ortho C-H fluoroalkoxylation of 4-aryl-pyrrolo[2,3-d]pyrimidines

A palladium-catalysed direct arene C-H fluoroalkoxylation of 4-aryl-pyrrolo[2,3-d]pyrimidine derivatives with fluorinated alcohols is described. Highly site-selective mono- or bis-fluoroalkoxylation can be achieved by tuning the reaction conditions, affording various fluoroalkoxylated pyrrolo[2,3-d]pyrimidine derivatives in moderate to good yields, which offer rational tailoring of their biological activity for their application in the field of pharmaceutical chemistry.

Skeletal Editing of Pyrimidines to Pyrazoles by Formal Carbon Deletion

A method for the conversion of pyrimidines into pyrazoles by a formal carbon deletion has been achieved guided by computational analysis. The pyrimidine heterocycle is the most common diazine in FDA-approved drugs, and pyrazoles are the most common diazole. An efficient method to convert pyrimidines into pyrazoles would therefore be valuable by leveraging the chemistries unique to pyrimidines to access diversified pyrazoles. One method for the conversion of pyrimidines into pyrazoles is known, though it proceeds in low yields and requires harsh conditions. The transformation reported here proceeds under milder conditions, tolerates a wide range of functional groups, and enables the simultaneous regioselective introduction of N-substitution on the resulting pyrazole. Key to the success of this formal one-carbon deletion method is a room-temperature triflylation of the pyrimidine core, followed by hydrazine-mediated skeletal remodeling.

Hydrogen Evolution Enabled Rhodaelectro-Catalyzed [4+2] Annulations of Purines and 7-Deazapurines with Alkynes

A rhodium-catalyzed electrochemical regioselective annulation of 6-phenylpurines and 6-phenyl-7-deazapurines with alkynes has been developed. Electricity is used to recycle the active rhodium-based catalyst, promote the evolution of H2 and help...

Pd-Catalyzed solvent-controlled site-selective arene C-H monoacyloxylation of pyrrolo[2,3-d]pyrimidine derivatives

An efficient and highly regioselective Pd-catalyzed direct arene C(sp²)-H acyloxylation of pyrrolo[2,3-d]pyrimidine derivatives is reported. The key strategy involves the utilization of the unique reactivity of pyrrolo[2,3-d]pyrimidine and the employment of pyrrolo[2,3-d]pyrimidine as the directing group. A variety of monoacyloxylated pyrrolo[2,3-d]pyrimidine derivatives can be achieved by switching the solvents under mild conditions, and they can be further modified and exhibit various biological activities.

An isoxazole strategy for the synthesis of alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylates - versatile building blocks for assembling pyrrolo-fused heterocycles

A full atom-economical domino method has been developed for the preparation of alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylates by transannulation of 5-alkoxyisoxazoles with malononitrile under Fe(ii) catalysis. Alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylates are excellent building blocks for various annulation reactions, leading to new derivatives of 1H-pyrrolo[1,2-a]imidazole and pyrrolo[2,3-d]pyrimidine. The DFT calculations of mechanistic details of alkyl 5-amino-4-cyano-1H-pyrrole-2-carboxylate formation are presented.

Transition-metal-free highly regioselective C–H acetoxylation of pyrrolo[2,3-d]pyrimidine derivatives

Transition-metal-free catalyzed direct C(sp²)–H acetoxylation of pyrrolo[2,3-d]pyrimidine derivatives is reported. This protocol provides a variety of acetoxylated pyrrolo[2,3-d]pyrimidines in good to excellent yields.