Methyl 1,2‐Orthoesters in Acid‐Washed Molecular Sieves Mediated Glycosylations

Abstract

Glycosylation of alcohol derivatives with D‐mannose and D‐glucose derived methyl 1,2‐orthobenzoates can be promoted by commercially available acid‐washed 300 molecular sieves (AW‐MS), which functions both as promoter and as a drying agent in an operationally simple process. In this manner, glycosides can be obtained in good to excellent yields at room temperature, reflux, or under microwave (MW) heating. The usefulness of the process has been shown with the preparation of some diterpene glycosides.

In Vitro Antimicrobial Activity of Isopimarane-Type Diterpenoids

“…Compounds 1 – 6 and 9 were isolated from Aeollanthus rydingianus aerial parts [ 19 ]. The benzoylated glycosides of compounds 10 – 12 were prepared as described by Uriel et al [ 20 ]. Compounds 7 , 8 and 10 – 12 were prepared as described below.…”

A Concise Synthesis of a BODIPY-Labeled Tetrasaccharide Related to the Antitumor PI-88

“…In those approaches, different types glycosyl donors have been employed. We have been interested in the use of 1,2-methyl orthoesters (MeOEs) [ 29 , 30 , 31 , 32 , 33 ] as an inexpensive alternative to Fraser–Reid’s n -pentenyl orthoester glycosyl donors (NPOEs) [ 34 , 35 , 36 ]. The former derivatives were shown to display good regioselectivity, similar to that of NPOEs [ 31 ].…”

A Malonyl-Based Scaffold for Conjugatable Multivalent Carbohydrate-BODIPY Presentations

“…Based on the well-studied chemistry of malonate diesters [58], the sequential bis-alkylation of dimethyl malonate ( 4 ) with pentenyl bromide and propargyl bromide paved the way to, previously unreported, ene-yne derivative 5 (Scheme 1). Subsequent LiAlH 4 -mediated reduction of 5 led to diol 6 , which was then glycosylated with readily prepared methyl orthoester (MeOE) 7 [59,60] (acid washed molecular sieves (AWMS), microwave irradiation) to furnish dimannan 8 in acceptable yield (Scheme 1) [60].…”