Prostaglandins and prostaglandin intermediates. 25. Synthesis of PGF2α Intermediates by addition of 1-metalated hept-1-ynes to a substituted cyclopentanecarbaldehyde bearing already the complete carboxylic side chain
✍ Scribed by Dr. Rainer Mahrwald; Prof. Dr. sc. nat. Hans Schick; Dr. Ludmila L. Vasil'eva; Dr. Kasimir K. Pivnitsky; Chemieingenieur Gisela Weber; Prof. Dr. sc. nat. Sigfrid Schwarz
- Publisher
- John Wiley and Sons
- Year
- 1990
- Tongue
- English
- Weight
- 449 KB
- Volume
- 332
- Category
- Article
- ISSN
- 1615-4150
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✦ Synopsis
Abstract
Starting with the racemic aldehyde 4, prepared from the tris(trimethylsilyl) ether 3, the possibility was demonstrated of converting a trimethylsilylated primary hydroxy group with high selectivity into an aldehyde group in the presence of two trimethylsilylated secondary hydroxy groups employing oxalyl chloride and dimethyl sulfoxide (Swern reagent) as oxidant. The alkynylation of this aldehyde with 1‐metalated hept‐1‐yne afforded a chromatographically separable mixture of two diastereomeric alcohols, both being suitable intermediates for the synthesis of PGF~2α~. The diastereofacial selectivity of the addition strongly depends on the metal employed. Hept‐1‐yn‐1‐yllithium afforded a 67:33 mixture of (13 R*)‐ and (13 S*)‐alcohol, hept‐1‐yn‐1‐yltriisopropoxytitanium, however, a 30:70 mixture.