 The asymmetric Diels-Alder reaction with acrolein 3 is carried out with the McMillan catalyst to the aldehyde 4 as the endo isomer which is oxidized to the carboxylic acid 5 with sodium chlorite, monopotassium phosphate and 2-methyl-2-butene.Addition of bromine gives halolactonization product 6 and after replacement of the Cbz protective group by a BOC protective group in 7 (hydrogenolysis in the presence of di-"tert"-butyl dicarbonate) a carbonyl group is introduced in intermediate 8 by catalytic ruthenium(IV) oxide and sacrificial catalyst sodium periodate.Addition of ammonia cleaves the ester group to form amide 9 the alcohol group of which is mesylated to compound 10.