Tetrahydrofuran compounds

Reagents i, PhjP-CCb ii, Bu3SnH iii, pyridinium chlorochromate iv, CrCl v, NaBH vi, TsCl-py vH, MejN viii. Cl 

Two syntheses of (+)- and (—)-(5)-nonactic acid have been reported. One uses a furanoid glycal as starting material, and the other the furanoside (6) which led to the (—)-isomer of the product and which also could be inverted at C-4 to give a ketone from which the (+)-isomer was obtained.  

Compound (10) is the (—)-enantiomer of anhydromyriocin, the 7-lactone of m iocin (thermazymocidin), and has been synthesized from L-arabinose.  

D-(-)-Muscarine iodide (1) has been prepared from 2-deoxv-D-erythro pentose via the acid derivative (2) by sequential lithium aluminium hydride reduction and quaternization. Likewise, L-(+)-allomuscar-ine was produced from the x epimer of (2), and 2-deoxy-L-erythro- 

Modified prostaglandins (11-deoxy-ll-oxa analogues of prostaglandin 2 and p2 ) have been prepared from standard glycos- 

3-ulose derivatives of D-glucofuranose and D-xylofuranose, e.g., the analogue (10) via the branched-chain intermediate (11) 

---

Among the heterocyclic compounds, there are aromatic, e.g. pyridine, as well as nonaromatic, e.g. tetrahydrofuran, compounds. Similarly, there are saturated (e.g. tetrahydrofuran) and unsaturated (e.g. pyridine) heterocyclic compounds. Heterocycles also differ in their ring sizes, e.g. pyridine has a six-membered ring, whereas tetrahydrofuran is a five-membered oxygen-containing heterocyclic compound. 

Important naturally occurring tetrahydrofuran compounds which have attracted much attention in recent years as synthetic goals are the ionophores, some possessing considerable antibiotic activity examples include monensin (196) (79JA260), nonactin (194) (76CB2628) and lasalocid A (195) (78JA2933). 

In the tetrahydrofuran compounds there is opportunity for the existence of cis and irans isomers. They have been separated81 in the case of XL and XLII, the cis-form of which forms an anhydride. Evidence for the existence of the cts-form of 2,5-dishydroxymethyltetra-hydrofuran (XXXVIII) is found in the behavior of either its dichloro-or di-toluene-p-sulfonyl derivative with methanolic ammonia. From this reaction the dicyclic compound, 8-oxa-3-aza6fcyeZo [3,2,1] octane (XLIII) is obtained which can have been formed only from the m-form of the dicarbinol.82 An example of the addition of bromine to the furan... 

Since then, several qinghaosu derivatives have been treated with ferrous sulfate in the same reaction condition. Except for some hydrolysis products, similar derivatives of tetrahydrofuran compound 28 and 3-hydroxy deoxyqinghaosu 15 were... 

Figure 7.11 Chromatograms of a mixture of amino acids and peptides eluted with 0.02 M SDS mobile phases containing (a) 3% 2-propanol, (b) 12.5% acetonitrile, and (c) 3% tetrahydrofuran. Compounds (1) tyrosine, (2) methionine, (3) alanyi-tyrosine, (4) tryptophan, (5) aspartyl-phenylalanine, (6) leucyl-tyrosine, and (7) glycyl-leucyl-tyrosine. Reprinted from Ref 10 with permission of Elsevier.

We employed this reaction to stereoselectively synthesize 2,3,4,5-tetrasubstituted tetrahydrofuran compounds. Treating one major product (147a R = Ph, R" = Me) with LiN(SiMe3)2 selectively generates cis-eno-late anion A that condenses with aldehydes, presumably via a cyclic... 

---