Werner Rank

The total synthesis of (±)erigerol

Abstract The labdane diterpenoid Erigerol and diastereoisomers thereof were synthesised in a 23 step sequence.

Synthesis of 5-acetamido-6,6-dibromo-5,6-dideoxy-6- nitrohexofuranose derivatives by addition and substitution reactions. N-bromoacetamide

Abstract N-Bromoacetamide, in the presence of a catalytic amount of sodium acetate, reacted smoothly with the nitroalkene moiety of 3-O-acetyl-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-α- D -xylo-hex-5-enofuranose (1) by addition of bromine and an acetamido group across the olefinic double bond, with concomitant introduction of a second bromine atom at C-6. The preponderant product was 5-acetamido-3-O-acetyl-6,6-dibromo-5,6-dideoxy-1,2-O-isopropylidene-6-nitro-α- D -glucofuranose (3). The β- L -ido isomer (4) and the 5-acetoxy analog (2) of 3 were isolated as minor products. Reaction of 1 with ammonia in tetrahydrofuran gave 5-acetamido-5,6- dideoxy-1,2-O-isopropylidene-6-nitro-α- D -glucofuranose (5) and -β- L -idofuranose (6) in a ratio of 1:1.4. These compounds were converted into their 3-acetates (7 and 8) which, with N-bromoacetamide, underwent bromination at C-6 to give 3 and 4, respectively. Configurations were allocated to the new products on the basis of circular dichroism.