Metalated heterocycles and their applications in synthetic organic chemistry.

Transmetalation of Unsaturated Carbon Nucleophiles from Boron-Containing Species to the Mid to Late d-Block Metals of Relevance to Catalytic C−X Coupling Reactions (X = C, F, N, O, Pb, S, Se, Te)

Recent developments in the synthesis of prostaglandins and analogues.

Cross-Coupling of Aryl Halides and Allyl Acetates with Arylboron Reagents in Water Using an Amphiphilic Resin-Supported Palladium Catalyst.

The cyclopentenone unit is a very powerful synthon for the synthesis of a variety of bioactive target molecules. This is due to the broad diversity of chemical modifications available for the enone structural motif. In particular, chiral cyclopentenones are important precursors in the asymmetric synthesis of target chiral molecules. This Review provides an overview of reported methods for enantioselective and asymmetric syntheses of cyclopentenones, including chemical and enzymatic resolution, asymmetric synthesis via Pauson-Khand reaction, Nazarov cyclization and organocatalyzed reactions, asymmetric functionalization of the existing cyclopentenone unit, and functionalization of chiral building blocks.

Synthesis of Chiral Cyclopentenones.

To construct a new strategy for synthesis of cyclopentanoids, the transition metal-catalyzed coupling reaction of cis 4-cyclopentene-1,3-diol monoacetate 1 with hard nucleophiles, RT−m, was investigated (eq 1 in Chart 1). Although preliminary experiments using PhZnCl, PhSnMe3, [Ph-B(Me)(OCH(Me)CH(Me)O)]-Li+ (6a) (derived from boronate ester 4a (RT = Ph) and MeLi) in the presence of a palladium or a nickel catalyst resulted in production of unidentified compounds, enone 16, and/or ketone 17 or recovery of 1, a new borate 5a (derived from 4a and n-BuLi) in the presence of a nickel catalyst (NiCl2(PPh3)2) in THF at room temperature furnished the trans coupling products 2a (RT = Ph) and 3a (RT = Ph) in high combined yield, but with a low product ratio of 0.9:1. The ratio was improved to 13:1 by addition of t-BuCN and NaI into the reaction mixture. This is the first successful example of the reaction of 1 with a hard nucleophile, and the increase in the ratio, realized with the additives, is unprecedented. Thi...

A New Method for Installation of Aryl and Alkenyl Groups onto a Cyclopentene Ring and Synthesis of Prostaglandins

Coupling reaction of 4-cyclopentene-1,3-diol monoacetate and lithium alkenylborates and its application to chiral synthesis of prostaglandin intermediates

Realization of high regioselectivity in the coupling reaction of a cyclopentadiene monoepoxide equivalent and aryl nucleophiles

Lithium alkenylborates couple with the monoacetate of 4-cyclopentene-1,3-diol under the nickel catalyst regioselectively and stereospecifically to afford trans 1,3-isomers in good yields. Moreover, an unexpectedly high level of regio-selectivity is observed with the alkenylborates possessing the prostaglandin (PG) ω-chain structure. The present reaction is successfully applied to the asymmetric synthesis of PG intermediates 9, 15, 16 .

Coupling Reaction of 4‐Cyclopentene‐1,3‐diol Monoacetate and Lithium Alkenylborates and Its Application to Chiral Synthesis of Prostaglandin Intermediates.

Coupling reaction of monoacetate 2 and aryl hard nucleophiles is realized for the first time, which consists of the lithium arylborates as hard nucleophiles and NiCl2(PPh3)2 as a catalyst. More importantly, the independent effects of t-BuCN and NaI and their synergistic function are discovered to increase regioselectivity furnishing trans 1,3-isomers 6 as the major products.

Shahid B. Usmani

Papers

A New Method for Installation of Aryl and Alkenyl Groups onto a Cyclopentene Ring and Synthesis of Prostaglandins

Coupling reaction of 4-cyclopentene-1,3-diol monoacetate and lithium alkenylborates and its application to chiral synthesis of prostaglandin intermediates

Realization of high regioselectivity in the coupling reaction of a cyclopentadiene monoepoxide equivalent and aryl nucleophiles

Coupling Reaction of 4‐Cyclopentene‐1,3‐diol Monoacetate and Lithium Alkenylborates and Its Application to Chiral Synthesis of Prostaglandin Intermediates.

Realization of High Regioselectivity in the Coupling Reaction of a Cyclopentadiene Monoepoxide Equivalent and Aryl Nucleophiles.