Diols, α-Ketols, and Diones as 2_2π Components in [2+2+2] Cycloadditions of 1,6-Diynes via Ruthenium(0)-Catalyzed Transfer Hydrogenation

Abstract

The first use of vicinal diols, ketols, or diones as 2 2π components in metal-catalyzed [2+2+2] cycloaddition is described. Using ruthenium(0) catalysts, 1,6-diynes form ruthenacyclopentadienes that engage transient diones in successive carbonyl addition. Transfer hydrogenolysis of the resulting ruthenium(II) diolate mediated by the diol or ketol reactant releases the cycloadduct with regeneration of ruthenium(0) and the requisite dione.

Ruthenium(0)‐Catalyzed Cycloaddition of 1,2‐Diols, Ketols, or Diones via Alcohol‐Mediated Hydrogen Transfer

“…[2c,2e,25] In the presence of ruthenium(0) catalysts, 1,6-diynes form ruthenacyclopentadienes that participate in successive carbonyl addition with transient diones derived from diol reactants to form products of [2+2+2] cycloaddition (Table 4). [14] Structurally diverse cyclic and acyclic diols deliver cycloadducts with complete levels of syn -diastereoselectivity as determined by 1 H NMR analysis. A carboxylic acid cocatalyst was again required to enhance rate and conversion.…”

“…This pattern of reactivity served as the basis for the design of redox-independent cycloadditions between 1,2-diols, ketols or diones with unsaturated partners, including acyclic 1,3-dienes, [10] cyclic 1,3-dienes, [11] norbornadienes and trienes, [11] α,β-unsaturated esters, [12] benzannulated diynes [13a] and acetylenic aldehydes, [13b] 1,6-diynes [14] and benzocyclobutenones (Figure 2). [15] In this review, we provide an overview of transfer hydrogenative cycloadditions to form fused and bicyclic carbocyclic ring systems via metal catalyzed cycloadditions.…”

Benzannulation through Ruthenium(0)‐Catalyzed Transfer Hydrogenative Cycloaddition: Precision Synthesis and Photophysical Characterization of Soluble Diindenoperylenes

“…Existing strategies for the synthesis of diindenoperylenes all involve Diels–Alder cycloadditions and the reported routes do not deliver highly soluble materials . In connection with our efforts toward the development of catalytic alcohol‐mediated C−C bond formations, ruthenium(0)‐catalyzed cycloadditions of vicinally dioxygenated hydrocarbons (diols, ketols, diones) were discovered, including an unusual ruthenium(0)‐catalyzed [2+2+2] cycloaddition wherein 1,6‐diynes react with 1,2‐diones (or diols/ketols) . Whereas numerous examples of [2+2+2] cycloadditions that occur by π‐bond insertion–reductive elimination of metallacyclopentadienes exist, the [2+2+2] cycloadditions we report are the first examples of the use of diones as 2 2π components (Figure ) .…”

Synthesis and Photophysical Properties of Soluble N‐Doped Rubicenes via Ruthenium‐Catalyzed Transfer Hydrogenative Benzannulation

“…[7n,v] Furthermore, to our knowledge,o nly as ingle report detailst he synthesis of highly soluble derivativest hat retain the desirable properties of the parent compound. [7s] In the course of developing transferh ydrogenative CÀCc ouplings, [8] ruthenium-catalyzed [4+ +2] cycloadditionso fv icinal diols, ketols, or diketones with dienes, [9] 1,6-diynes [10] and other p-unsaturated partners [11] were developedi no ur laboratory. [12] The diol-containing cycloadducts readily undergo dehydration (or deoxydehydration) to form aromatic rings, unlocking an ew benzannulations trategy that has openedn ovel synthetic routest oa cenes, [13a] oligo(phenylene) cages, [13b,c] nanographenes, [13d] and diindenoperylenes.…”