Of macrolide

This method is based on the generation of the tetraalkylammonium salt of pyrrolidorle, which acts as a base. The method is compatible with a large variety of carboxylic acids and alkylating agents. The method is effective for the preparation of macrolides. 

Total synthesis of macrolide immunodepressants using 1,3-dithiane aldol couplings and a-bond olefin constructions 98ACR35. 

Oxazol-5(4//)-ones as intermediates in the formation of macrolides, cyclodep-sipeptides, and cyclopeptides 99JHC1539. 

Hydrolysis of macrolides by products of the ere genes detected in enterobacteria is only of scientific interest, while esterases VGB-A and VGB-B encoded by the vgb type genes mediate clinically relevant resistance in staphylococci to the B compound (quinupristin) of the streptogramin combination quinu-pristin-dalfopristin. 

Tacrolimus (TRL), in the past also named FK506, belongs to the group of macrolides and is produced by a special actinomycete species. TRL binds to its cytosolic receptor FKBP-12, however, it also blocks calcineurin activity and subsequently cytokine synthesis. 

The utility of RCM methodology for the synthesis of open-chain building blocks from a,fi-unsaturated d-lactones is exemplified by the partial syntheses of Cossy aimed for (+)-methynolide (the aglycon of the methymicin family of macrolide antibiotics) [45], and the anticancer agent discodermolide [46], as well as during a recent total synthesis of the highly cytotoxic marine natural depsipeptide apratoxin A by Forsyth and Chen [47]. 

Scheme 78 Novel ring-contraction metathesis of macrolide antibiotics with a 1,3-diene moiety [164]...

For a high-yielding ring contraction in the series of macrolide antibiotics containing a 1,3-diene unit, see Scheme 78... 

McArdell CS, Molnar E, Suter MJF, Giger W (2003) Occurrence and fate of macrolide antibiotics in wastewater treatment plants and in the Glatt Valley watershed, Switzerland. Environ Sci Technol 37(24) 5479-5486... 

Loganathan B, Phillips M, Mowery H, Jones-Lepp TL (2009) Contamination profiles and mass loadings of macrolide antibiotics and illicit drugs from a small urban wastewater treatment plant. Chemosphere 75(l) 70-77... 

Fig. 5.11 Erythromycins erythromycin is a mixture of macrolide antibiotics consisting largely of erythromycin A.

There are at least three types of PKS. Type I PKSs catalyze the biosynthesis of macrolides such as erythromycin and rapamycin. As modular enzymes, they contain separate catalytic modules for each reaction catalyzed sequentially in the polyketide biosynthetic pathway. Type II PKSs have only a few active sites on separate polypeptides, and the active sites are used iteratively, catalyzing the biosynthesis of bacterial aromatic polyketides. Type III are fungal PKSs they are hybrids of type I and type II PKSs [49,50]. 

Borisova, S., Zhao, L., Melancon, C.E. et al. (2004) Characterization of the glycosyltransferase activity of desVII analysis of and implications for the biosynthesis of macrolide antibiotics. Journal of the American Chemical... 

Uyama H, Kobayashi S (1996) Enzymatic ring-opening polymerization of macrolides to polyesters. In Yalpani M (ed) Biomedical functions and biotechnology of natural and artificial polymers. ATL Press, Schrewsbury, p 5... 

Elaboration of triol 88b to bryostatin 7 requires chemoselective hydrolysis of the Cl methyl ester in the presence of the C7 and C20 acetates, macrolide formation, installation of the C13 and C21 methyl enoates, and, finally, global deprotection. The sequencing of these transformations is critical, as attempts to introduce the C21 methyl enoate to form the fully functionalized C-ring pyran in advance of macrolide formation resulted in lactonization onto the C23 hydroxyl. In the event, trimethyltin hydroxide promoted hydrolysis [73] of the Cl carboxylate of triol 88b, and subsequent trie thy lsilylation of the C3 and C26 hydroxyls each occurs in a selective fashion, thus providing the seco-acid 89. Yamaguchi macrolacto-nization [39] proceeds uneventfully to provide the macrolide 67 in 66 % yield (Scheme 5.14). 

Compound 17 is the so-called (+)-Prelog-Djerassi lactonic acid derived via the degradation of either methymycin or narbomycin. This compound embodies important architectural features common to a series of macrolide antibiotics and has served as a focal point for the development of a variety of new stereoselective syntheses. Another preparation of compound 17 is shown in Scheme 3-7.11 Starting from 8, by treating the boron enolate with an aldehyde, 20 can be synthesized via an asymmetric aldol reaction with the expected stereochemistry at C-2 and C-2. Treating the lithium enolate of 8 with an electrophile affords 19 with the expected stereochemistry at C-5. Note that the stereochemistries in the aldol reaction and in a-alkylation are opposite each other. The combination of 19 and 20 gives the final product 17. 

Bridging of macrolides.1 A number of natural products are known to consist of oxapolycyclic systems. A potential route to such systems involves bridging of the more readily available macrolides (or the corresponding dithionolides, available by thionation with Lawesson s reagent) by electron-transfer reactions initiated with sodium naphthalenide (Scheme I). 

Radical cyclization to macrolides.111 Cyclization of iodoalkyl acrylates (1) by reaction with Bu3SnH (1 equiv.) in the presence of AIBN is useful for formation of macrolides (2) containing 11 or more members. Similar cyclization of iodoalkyl fumarates (3) results in two macrolides with the endo-product predominating except when n is 16 or higher. Tertiary iodides undergo this free radical cyclization more... 

Biological properties of ethylene, 70 598-599 of macrolide antibiotics, 75 302-305 of sutures, 24 216-218 Biological recycling technologies, in wastewater treatment, 25 889t, 895-902... 

Biosynthetic patterns, of macrolide antibiotics, 15 305-306 Biota, circulation of water with, 26 7-12 Biotechnological manufacturing, key characteristics of, ll 440t Biotechnological membrane applications, 15 848... 

Tobback, K., Li, Y.-M., Pizarro, N. A., De Smedt, I., Smeets, T., Van Schepdael, A., Roets, E., and Hoogmartens, J. (1999). Micellar electrokinetic capillary chromatography of macrolide antibiotics separation of tylosin, erythromycin and their related substances.. Chromatogr. A 857, 313-320. 

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