Studies on the Preparation of Protomycinolide IV: Enantioselective Synthesis of the C3–C9 Segment

The C3–C9 segment, (−)-16, of the polyene macrolide antibiotic protomycinolide IV (1a) was prepared in optically pure form from commercially available methyl (S)-2-methyl-3-hydroxypropionate in 12 steps giving 17% yield

Studies Directed Towards the Synthesis of Protomycinaolide IV

Tricarbonyl(diene )iron complexes have been known for over 65 years but have only recently received attention concerning their use in organic synthesis. Several research groups have further shown that acyclic butadiene-iron complexes can be used in asymmetric organic syntheses as well. Furthermore, transition metal dienone complexes are beginning to receive more attention in regards to their use in organic synthesis. However, there appears to be a lack of information on the use of enolates derived from tricarbonyl- (dienone)iron complexes. Therefore, formation of a stabilized tricarbonyl(dienone)iron enolate complex and whether such a species will react with various electrophiles in a stereospecific manner needs to be addressed

Alkylation of Tricarbonyl(diene)iron Complexes: Model Studies for the Preparation of Protomycinolide IV

The alkylation of (4,6-heptadien-3-one)- and (methyl 3,5-hexadienoate)Fe(CO)3 (1 and 2) were examined (0–42% de and 69–92% de respectively). Optically active (methyl 3,5-hexadienoate)Fe(CO)3 (−)-2 was prepared by resolution of the corresponding carboxylic acid complex with α-methylbenzylamine. The alkylation of (4,6-heptadien-3-one)-Fe(CO)3 (1, 0–42% de) and (methyl 3,5-hexadienoate)Fe(CO)3 (2, 70–92% de) were examined