Pseudosugars, 35. Synthesis of glycosylceramide analogs composed of imino‐linked unsaturated 5a‐carbaglycosyl residues: Potent and specific gluco‐ and galactocerebrosidase inhibitors

5a‐Carba‐β‐glucosyl‐ E ‐3 and galactosylceramide analogs E ‐ 4 were synthesized by coupling of the protected derivatives 5 of β‐valienamine and 15 of 4‐epi‐β‐valienamine with the aziridines E ‐ 6 and Z ‐ 6 , as the sphingosine precursors, respectively, and subsequent deprotection and N ‐acylation. Both the new analogs and their corresponding Z ‐isomers Z ‐ 3 and Z ‐ 4 were shown to be very potent and specific gluco‐ and galactocerebrosidase inhibitors, and, interestingly, the Z ‐isomers possess inhibitory activity comparable to that of the corresponding E ‐isomers.