Prop anal

The key step for the synthesis of aspyrone involves the reaction of an a-phenylselanyl 6-lactone enolate and fi j-2-tosyl prop anal with subsequent stereospecific formation of epoxide [49] (Scheme 40). 

Prop. Anal. Chem. 1979, 51-62 Kumanotani, J. Proc. 182nd Nat. Meet. Am. Chem. Soc., 1981. 

Nakasato, T. Proc. Int. Symp. Cult. Prop. Anal. Chem. 1980, 113-24. d Argence, R. Apollo 1980, 112, 6-19. 

Masamune has also completed a synthesis of tylonide hemiacetal (291) based on the creative use of enantioselective aldol condensations, as shown in Scheme 2.26. The aldol condensation of 328, derived from (/f)-hexahydromandelic acid and prop anal, was found to be >100 1 diastereoselective, affording the 2,3 syn compound 329 in 97% yield. Transformation to the p,7-unsaturated ester 330 occurred via selenoxide elimination and periodate cleavage followed by esterification. Formation of the silyl ether, reduction, and protection of the ester followed by ozonolysis of the terminal olefin gave the diol-protected aldehyde 331. The C-11 to C-15 segment 332 was then completed via chain elongation and a subsequent reduction-oxidation sequence in 34% overall yield from 330. 

Ethan al Prop anal 2-Ethyl-4irn ihylpentanal... 

Prop. Anal. detn. by double titration with CHarCHCHaBr (68a, 173) with RBr... 

Synth. By rxn. of Et3SnCl with CH2 CHCH2MgCl in Et20, in 76% yield (I367). Prop. Anal. detn. by GLC (I376), by iodometric titration (I619)-Rxn. with HCl in aq. MeOH kinetic and thermodynamic data on olefin cleavage rxn. (1367). 

Prop. Anal. detn. and complex formation [MeSnFa+n]by anionic paper chromatography and paper electrophoresis n 1-2 (71). 

Prop. Anal. detn. with alizarin S (7O), by potentiometry in presence of HCIO4 and Nad or NaBr (255 ) ... 

Diethyltin Dicaprylate SnC2oH4o04 Et2Sn(02CC7Hi5-n)2 Prop> Anal. detn. by B-ray reflection method (687), by polarography (2265), with diphenylcarbazone ( 90) ... 

Brewer, G.A. et al. Anal. Profiles Drug Subst., 1977, 6, 183 (rev, synth, props, anal)... 

---