Synthesis of configurationally chiral cryptands and cryptates from carbohydrate precursors

Abstract

Optically pure configurationally chiral 18-to the development of so-called host-guest chemistry2 by crown-6 and 9-crown-3 cryptands have been synthesised Cram et aL3 Carbohydrates and their derivatives are not from L-tartaric acid and D-mannitol and some of the 18-only rich in substituted bismethylenedioxy units for crown-6 derivatives have been shown to form cryptates incorporation into the 18-crown-6 constitution but they also with metal and primary alkylammonium cations.provide a relatively inexpensive source of chirality for synthesising hosts with potential for exhibiting chiral recognition towards enantiomeric guests. This prospect has now been realised by utilising L-tartaric acid and D-THE ability1 of macrocyclic polyethers of the 18-crown-6 type t o complex with primary alkylammonium salts has led

Molecular Receptors. Functionalized and chiral macrocyclic polyethers derived from tartaric acid

“…The product 4b obtained was difficult to purify and was converted to its more easily purified derivative 4c. Compound 4b has also been prepared independently in a different approach based on the use of sugar units [19]. The tetraacetic acid derivative 4e has been obtained from 4b by a series of straightforward reactions [24] Physical and spectral properties, The tartro-crowns obtained from the cyclizations are generally well crystallized with sharp melting points.…”

Sugar Derived Crown Ethers and Their Analogs: Synthesis and Properties

“…Stoddart [5] prepared such receptors from 1,2:5,6-di-O-isopropylidene-D-mannitol, in a sequence of reactions involving: allylation of the free hydroxyl groups, ozonolytic cleavage of both double bonds followed by reduction ( 6 8 ), tosylation ( 69), and subsequent reaction of both fragments leading finally to the D 2 -symmetrical macrocycle 70 (Scheme 13).…”

“…No wonder, that such chirons were used for the preparation of enantiomerically pure macrocyclic receptors. In 1975 a paper by Stoddart, describing synthesis of chiral crown ethers with incorporated sugar unit appeared in the literature [5], and was quickly followed by further papers from this group [6][7][8][9][10]. Variety of oxymethylene units present in each molecule of simple sugars (or their derivatives), allows to incorporate monosaccharides into the structure of crown ethers, which differ in size and flexibility of the macrocyclic ring.…”

Synthesis of d‐mannitol‐based crown ethers and their application as catalyst in asymmetric phase transfer reactions

“…15,17 The starting compounds for the synthesis of D-mannitol-based macrocycles were 1,2:5,6-di-O-isopropylidene-D-mannitol, 1,2:5,6-di-O-diphenylmethylidene-D-mannitol (3), and 1,2:5,6-di-Ocyclohexylidene-D-mannitol (4). 15,17 The starting compounds for the synthesis of D-mannitol-based macrocycles were 1,2:5,6-di-O-isopropylidene-D-mannitol, 1,2:5,6-di-O-diphenylmethylidene-D-mannitol (3), and 1,2:5,6-di-Ocyclohexylidene-D-mannitol (4).…”

“…Cram et al was the first who published a phase transfer reaction, in which the asymmetric induction was established by a chiral crown ether catalyst. 15 In our group, the 1,2:5,6-di-O-isopropylidene-mannitol-based monoaza-15-crown-5 lariat ethers (2a-2b) were prepared and used in a few asymmetric syntheses as phase transfer catalysts, but the enantioselectivities achieved were only low to moderate (up to 40% ee). However, it is a real green chemical challenge to develop natural-based chiral catalysts.…”