The ring-closing metathesis of vinyl ethers with Grubbs' catalyst for the synthesis of dihydropyrans

The Tandem Ring‐Closing Metathesis–Isomerization Approach to 6‐Deoxyglycals

“…[14][15][16] While most glycal syntheses rely on reductive elimination of glycosides in one way or the other, [17,18] over the past few years transition metal mediated or catalyzed cyclization reactions became more and more important. In particular, the cyclization of alkynols [19][20][21] and the ring-closing metathesis [22][23][24] of enol ethers [25][26][27][28][29] has attracted considerable attention. The observation that the well established ruthenium-based metathesis catalysts sometimes catalyze other reactions with comparable efficiency [30,31] has not only stimulated research directed at a deeper understanding of the degradation reactions of these complexes, [32,33] but has also led to the development of new metathesis-non-metathesis tandem sequenAbstract: Protected 3,6-dideoxyglycals have been synthesized de novo as single isomers starting from ethyl lactate by using the tandem RCM-isomerization reaction as the key step.…”

An improved asymmetric synthetic route to a novel triple uptake inhibitor antidepressant (2S,4R,5R)-2-benzhydryl-5-((4-methoxybenzyl)amino)tetrahydro-2H-pyran-4-ol (D-142)

“…O -Alkylation of 12 with allyl bromide in the presence of NaH produced compound 13 , which was converted into pyran derivative 14 by a ring-closing metathesis reaction in the presence of 1 st generation Grubbs catalyst. 16 The reaction of olefin 14 with N -bromoacetamide in aqueous dioxane produced bromohydrin 16 . It is perceivable that both diastereoisomers of the intermediate bromonium ion might exist in a very rapid equilibrium with each other.…”

A Survey of Synthetic Routes towards the Pyranonaphthoquinone Antibiotic Pentalongin and Syntheses of the Corresponding Nitrogen Derivatives

“…42 However, such a reaction of vinyl ethers containing alkoxy substituents was recently performed successfully by Wong. 43 As it appears to be that the oxidative demethylation of compound 80 is not successful, it was necessary to make a little detour. This problematic oxidation of certain pyranonaphthalene derivatives was already observed by us 36 and by others.…”