Udo Hedtmann

The first enzymatic degradation products of the antibiotic moenomycin A.

Abstract Moenomycin A was degraded by enzymatic cleavage of the bond between the moenuronic acid moiety and the phosphate group. The phosphoric acid monoester 4a could be dephosphorylated further to yield 3a . Compound 3a was used to confirm the previous configurational assignment at C-2 of the glycerate part of moenomycin A and to prepare ent - 4a . 4a and ent - 4a are antibiotically inactive.

A FACILE ROUTE TO 20-HYDROXYECDYSONE AND SIDE CHAIN HOMOLOGUES FROM POSTSTERON

Abstract A flexible approach to ecdysteroids, chain elongated at C-26 and C-27, is reported. Key features are the addition of 5-lithio 2,3-dihydrofurans (3) to poststeron (10) and a stereoselective reduction of the 22-∞ group.

A facile synthesis of the 20-hydroxyecdysone side chain via a dihydrofuran derivative

Abstract Key steps of a new synthesis of the 20-hydroxyecdysone side chain are (i) addition of 2 to 20-ketopregnanes and (ii) the stereoselective reduction of the 22-keto group after OH group protection.

Synthesis of potential ecdysteroid precursors from Δ7,22 sterols

Abstract Two routes for the conversion of 5α-cholest-7-ene-3β-ol (11) into 7, which has the typical ecdysteroid substitution pattern in rings B, C, and D, have been developed. Making use of one of the methods, 5,6-dihydroergosterol (31) was converted into the 38, possessing all the functionalities required for the synthesis of naturally occurring ecdysteroids.