An Unusual Ruthenium-Catalyzed Cycloisomerization of Alkynes and Propargyl Alcohols

Abstract

CpRu(NCCH3)3+PF6- catalyzes the cycloisomerization of diyne-ols to alpha,beta,gamma,delta-unsaturated aldehydes and ketones in good-to-excellent yields. 1-Hydroxy-2,7-diynes and 1-hydroxy-2,8-diynes can be utilized to form highly functionalized five- and six-membered rings, respectively. Tertiary as well as secondary propargyl alcohols are cycloisomerized to a single isomeric product. A wide variety of tether substitution can be tolerated. Even totally unsubstituted tethers can be employed, as geminal disubstituents are not required for cyclization. Additional hydroxyl substituents at an alternative "internal" propargylic position are eliminated during the reaction-a feature that leads to a convenient cyclopentadiene synthesis. Furthermore, 3-hydroxy-1,6-diynes also can be cyclized to form cross-conjugated aldehydes.

Click chemistry in materials synthesis. 1. Adhesive polymers from copper‐catalyzed azide‐alkyne cycloaddition

“…Compounds 8 , 9 , and 14 are commercially available; 16 was kindly provided by Dr. Jun‐Cai Meng. The following compounds are known and were prepared by the reported procedures with only slight adjustments: 2 ,18–21 10 ,22 11 ,23 12 ,24 13 ,25 and 15 26. The syntheses of monomers are summarized in Figure 1; synthetic procedures and characterization data for new compounds follows.…”

Ruthenium‐Catalyzed Reactions—A Treasure Trove of Atom‐Economic Transformations

“…(81)]. [238] In this case, a bicyclic product 348 is formed in very high yield in the presence of only 1 mol % of catalyst. In contrast to the intermolecular dimerization, even secondary and primary propargyl alcohols function well in this cycloisomerization reaction.…”

Ruthenium-Catalyzed Dimerization of 1,1-Diphenylpropargyl Alcohol to a Hydroxybenzocyclobutene and Related Reactions

“…They isolated a cyclobutadiene complex, which may be derived from reductive elimination form A, as the reaction intermediate. Trost and co-workers also described a ruthenacycle similar to A as a key intermediate in CpRu-catalyzed reactions of propargylic alcohols [27,28]. On the other hand, Chan and co-workers synthesized indene derivatives by the iron-catalyzed self-condensation of 1-arylpropargyl alcohols involving aromatic C-H bond cleavage [29].…”