Cyclodextrin chemical synthesis

The monoallyl derivative of P-cyclodextrin in its peracetylated form, namely mono-(6-N-allylamino)-6-deoxy)-peracetylated-P-cyclodextrin, was synthesized in 3 steps from native P-cyclodextrin. The synthesis of this derivative is reported in ref [20], The NMR and IR analyses were consistent with the expected chemical structure. 

Wakao, M, K Fukase and S Kusumoto (2002). Chemical synthesis of cyclodextrins by using intramolecular glycosylation. Journal of Organic Chemistry, 67,8182-8190. 

As before, this Chapter deals with specific trl- and higher saccharides most references related to their syntheses by specific chemical methods. It does not cover higher, non-specific compounds made by the oligomerisation of monosaccharide derivatives nor does it deal with the cyclodextrins. The synthesis of, e.g.. pentasaccharides is dealt with under that heading and the required preparations of constituent parts are assumed and are not covered in their sections. 

For a historically comprehensive review of the literature on the structure and properties of CDs and their inclusion complexes (both basics and applications) we refer to the special issue Cyclodextrins of Chem. Soc. Rev CD-based systems proved to be excellent tools for applications in chemical synthesis, analysis and separation science, biomimetic... 

The chemical synthesis and electrosynthesis of polypyrrole in the presence of sulfonated cyclodextrin as a dopant has been reported (52). In this case, cyclodextrin seems to play an important role in forming polymer with ordered structure. 

Enzymatic conversions have also found application in the resolution of racemic mixtures. When an organic synthesis involves a chiral center, one typically obtains a racemic mixture of the end products. Very commonly, chiral isomers differ in sensory properties, and one desires one enantiomer as opposed to the racemic mixture, e.g., L-menthol is the desired form of menthol. It is very diflicult to separate enantiomers by chemical means on a commercial basis (cyclodextrin-based colnnms have some utility in this application). However, a characteristic of enzymatic reactions is their stereospeciflcity, i.e., they will act on one enantiomer but not another. Thus, enzymatic processes may be incorporated into chemical synthesis to obtain a pure optical isomer. This may be done in either of two ways. 

Active substances belonging to the groups of crown ethers, cryptands, cyclodextrines and calixarenes are members of a relatively newbranch of science, the so-called Host-guest chemistry. The idea is that a small molecule or ion, the guest , is bound by electrostatic or van der Waals forces in the cavity of the host . The steric constitution of the host molecule is crucial This is a challenge for chemical synthesis. 

T. Furiuke, R. Sadamoto, K. Niikura, K. Monde, N. Sakairi, and S.-I. Nishimura, Chemical and enzymatic synthesis of glycocluster having seven sialyl lewis X arrays using /i-cyclodextrin as a key scaffold material, Tetrahedron, 61 (2005) 1737-1742. 

Cyclodextrins, products of the degradation of starch by an amylase of Bacillus macerans(1), have been studied in terms of chemical modifications, mainly for the purpose of developing efficient enzyme mimics(2). Not only their unique cyclic structures, but also their ability to form Inclusion complexes with suitable organic molecules, led us to Investigate the total synthesis of this class of molecules(3) We describe here an approach to a total synthesis of alpha(l), gamma(2), and "iso-alpha" cyclodextrin (3). 

Fig. 7. The total synthesis of a-cyclodextrin 30 by Ogawa [73a] was followed by his total synthesis of a manno-isomer 31 [73 b] of a-cyclodextrin 30. The potential for chemical variation of the cyclodextrin skeleton by total synthesis is considerable. The recent report of the peranhydro a-cyclodextrin 32 simultaneously by two groups [75] constitutes another important gross structural modification of the cyclodextrin skeleton...

All three techniques have been unequally exemplified in the separation of heterocyclic atropisomers. GC on a 10% permethyl-(-cyclodextrin (Chirasil-Dex, Chrompack) chemically bonded to a dimethyl polysiloxane backbone (CB-(-PMCD) coupled with El—MS was employed to elucidate the structure of a hexachlorinated bipyrrole which was obtained as a byproduct during the synthesis of the achiral heptachloro-1 ( -methyl-1,2 ( -bipyrrole (02AC4287). Two baseline separated peaks were obtained in ca. 20 min confirming the chiral structure of the by-product. 

Croft AP, Bartsch RA. (1983). Synthesis of chemically modified cyclodextrins. Tetrahedron 39 1417-1474. 

I. Nagashima, H. Shimizu, T. Matsushita, S. Nishimura, Chemical and enzymatic synthesis of neoglycoUpids in the presence of cyclodextrin. Tetrahedron Lett, 2008, 49, 3413-3418. 

Ashton, PR, SE Boyd, G Gattuso et al. (1995). A novel approach to the synthesis of some chemically-modified cyclodextrins. The Journal of Organic Chemistry, 60(12), 3898—3903. 

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