Prenalterol
Prenalterol is a cardiac stimulant which acts as a β adrenoreceptor agonist. Synthesis. Stereospecific. Prenalterol exhibits adrenergic agonist activity in spite of an interposed oxymethylene group. The stereospecific synthesis devised for this molecule relies on the fact that the side chain is very similar in oxidation state to that of a sugar. Condensation of monobenzone (2) with the epoxide derived from α--glucofuranose affords the glycosylated derivative (3). Hydrolytic removal of the acetonide protecting groups followed by cleavage of the sugar with periodate gives aldehyde (4). This is reduced to the glycol by means of NaBH and the terminal  alcohol is converted to the mesylate (5). Displacement of the leaving group with isopropylamine followed by hydrogenolytic removal of the "O"-benzyl ether affords the β-adrenergic selective adrenergic agonist prenalterol (6). Racemic. Prepns of the racemic mixture: corresp to H. Köppe et al., (1965, 1972 both to Boehringer Ingelheim); corresp to A. F. Crowther, L. H. Smith, (1965, 1970 both to ICI);