CpTiCl2 -Catalyzed Cross-Coupling between Internal Alkynes and Ketones: A Novel Concept in the Synthesis of Halogenated, Conjugated Dienes

A Concise Diastereoselective Total Synthesis of α-Ambrinol

(-)-cis-α-Ambrinol is a natural product present in ambergris, a substance of marine origin that has been highly valued by perfumers. In this paper, we present a new approach to its total synthesis. The starting material is commercially available α-ionone and the key step is an intramolecular Barbier-type cyclization induced by CpTiCl2, an organometallic compound prepared in situ by a CpTiCl3 reduction with Mn.

Dibromo-BODIPY as an Organic Photocatalyst for Radical-Ionic Sequences

A new dibrominated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is reported as a new metal-free photocatalyst. This BODIPY showed similar optoelectronic, electrochemical, and performance properties to those of Ru(bpy)₃Cl₂, one of the most common photocatalysts in a known radical-ionic transformation, such as the formation of 1,4-dicarbonyl compounds. Moreover, additional sequences in which the generated oxonium ion is trapped by an internal nucleophile were developed using this BODIPY photocatalyst. These new sequences allowed the straightforward preparation of γ-alkoxylactones, monoprotected 1,4-ketoaldehydes, and dihydrofurans. This new catalyst, the methodology, and the forged functional groups could be important tools in organic synthesis.

Ring Opening of Triflates Derived from Benzophospholan-3-one Oxides by Aryl Grignard Reagents as a Route to 2-Ethynylphenyl(diaryl)phosphine Oxides

A new simple method for the synthesis of 2-ethynylphenyl(diaryl)phosphine oxides via ring opening of benzophosphol-3-yl triflates has been developed. This process occurs via nucleophilic attack of a Grignard reagent at the phosphorus center, which results in ring opening and cleavage of a leaving group. The reaction proceeds under mild conditions and, within 15-60 min, leads to a library of previously unavailable 2-ethynylphenylphosphine oxides in yields up to 98%.

Deciphering the Chameleonic Chemistry of Allenols: Breaking the Taboo of a Onetime Esoteric Functionality

The allene functionality has participated in one of the most exciting voyages in organic chemistry, from chemical curiosities to a recurring building block in modern organic chemistry. In the last decades, a special kind of allene, namely, allenol, has emerged. Allenols, formed by an allene moiety and a hydroxyl functional group with diverse connectivity, have become common building blocks for the synthesis of a wide range of structures and frequent motif in naturally occurring systems. The synergistic effect of the allene and hydroxyl functional groups enables allenols to be considered as a unique and sole functionality exhibiting a special reactivity. This Review summarizes the most significant contributions to the chemistry of allenols that appeared during the past decade, with emphasis on their synthesis, reactivity, and occurrence in natural products.

A Titanium-Catalyzed Reductive α-Desulfonylation

A titanium(III)-catalyzed desulfonylation gives access to functionalized alkyl nitrile building blocks from α-sulfonyl nitriles, circumventing traditional base-mediated α-alkylation conditions and strong single electron donors. The reaction tolerates numerous functional groups including free alcohols, esters, amides, and it can be applied also to the α-desulfonylation of ketones. In addition, a one-pot desulfonylative alkylation is demonstrated. Preliminary mechanistic studies indicate a catalyst-dependent mechanism involving a homolytic C-S cleavage.