Macrocyclic polylactones

The total synthesis of protected enterobactin 10, developed by Shanzer and Libman [14 a], involves the use of organotin species as templates in the cyclooligomerization of ff-lactones to macrocyclic polylactones (Scheme 2) [14 b]. The [Bu2Sn(OCH2CH20)]2 acts like a homogeneous catalyst in this reaction. 

Kricheldorf, H.R. and Eggerstedt, S., MALDI-TOF Mass Spectrometry of Tin-Initiated Macrocyclic Polylactones in Comparison to Classical Mass Spectroscopic Methods, Macromol. Chem. Phys., 200, 1284, 1999. 

The ions of cobalt(III), rhoditun(III) and iridium(III) are the best templates for assembling octahedral complexes with ligands of the sepulchrate type. To obtain macrocyclic polylactones and polylactams, templates with covalent character bonds, such as Sn, Si, Sb, or B, are used. Copper(I) is the most convenient centre for the synthesis of catenanes. 

A unique approach to the controlled design of such systems as macrocyclic polylactones, polylactams and related compounds has been developed [1]. The synthesis of these substances, called biomimetic macrocyclic molecules by reason of their resemblance to naturally occuring ionophores (such as valinomycin, nonacdn, enniatin and enterobactin [2-5]), is carried out by a covalent-template method. This description arises from the use of elements forming covalent bonds (tin, silicon, antimony, boron) as matrices. 

Macrocyclic polylactones, poly lac tarns and related compounds 453... 

Macrocyclic polylactones L1577-L1581, possessing rotational symmetry and therefore called rotolactones [12], are obtained by reaction of distannoxanes with propiolactone in up to 80% yields (Eq. 7.6) [6, 9],... 

Macrocyclic polylactones, poly lactams and related compounds 457... 

The production of new macrocyclic systems has become possible due mainly to the development of new template centres for specific ligand products, such as the covalent-template approach to the synthesis of macrocyclic polylactones, polylactams and related compounds. Also of note is the the assembly of the cat-echoylamide systems H6L1019 and H6L1022 on an iron(III). In these situations the specific arrangement of functional groups required for macrocyclisation is a result of complex formation. 

Kricheldorf H R and Eggerstedt S (1998) Macrocycles 4. Macrocyclic polylactones as bifunctional monomers for polycondensations, JPolym Sci A Polym Chem 36 1373-1378. 

Kricheldorf H R and Eggerstedt S ((1999) Macrocycles 6. MALDI-TOF mass spectroscopy of tin-initiated macrocyclic polylactones in comparison to classical mass-spectro-scopic methods, Macromol Chem Phys 200 1284-1291. 

Kricheldorf FIR, Lee SR (1996) Polylactones. 40. Nanopretzels by macrocyclic polymerization of lactones via a spirocyclic tin initiator derived from pentaerythritol. Macromolecules 29 8669-8695... 

Kricheldorf HR, Lee SR (1995) Polylactones. 35. Macrocyclic and stereoselective polymerization of P-D,L-butyrolactone with cyclic dibutyltin initiators. Macromolecules... 

Macrocyclic polycarbonyls are cyclic ligands containing carbonyl functionalities. Several categories come under this heading the macrocyclic oligoketones (7), the polylactones (8) and the polylactams (9). 

Polyoxa macrocycles, known more commonly as the crown ethers, comprise an extensive area of research, with a repertoire of types and variations. Some of these macrocycles have been utilized predominantly for purposes other than metal ion complexation, and these will not be discussed in depth in this review. Included in this latter category are the polycarbonyls, polylactones,polylactams and carcerands. " ... 

Until now most covalent-template syntheses have been carried out to form macro-cyclic polylactones [1, 6-16]. The synthesis of tetralactones L1562-L1567 represented in Scheme 7-1 has been achieved in 30-85% yield [7, 10]. Other cyclic stannoxanes are also suitable for covalent-template synthesis of macrocyclic tetralactones, for example L1568 (Eq. 7.1) [10]. Tetralactones L1569 (Eq. 7.2) and L1570 (Eq. 7.3) are synthesised in an analogous way [10]. 

Kricheldorf, H.R. and Hauser, K. (1998) Macrocycles. Telechelic polylactones via macrocyclic polymerization. Macromolecules, 31,614—620. 

Dubois, Ph., Jacobs, C., Jerome, R., and Tessie, Ph., 1991, Macromolecular engineering of polylactones and polylactides. 4. Mechanism and kinetics of lactide homopolymerization by aluminum isopropoxide. Macromolecules 24 2266-2270 Kricheldorf, H. R., Lee, S., and Bush, S., 1996, Polylactones 36. Macrocyclic Polymerization of Lactides with Cyclic Bu2Sn Initiators Derived from 1,2-Ethanediol, 2-Mercaptoethanol, and 1,2-Dimercaptoethane. Macromolecules 29 1375-1381 Stevels, W. M., Dijkstra, and P. Feijen, J., 1997, New initiators for the ring-opening polymerization of cyclic esters. Trends Polym. Sci. 5 300-305. 

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