Process-Scale Total Synthesis of Nature-Identical (−)-(S,S)-7-Hydroxycalamenal in High Enantiomeric Purity through Catalytic Enantioselective Hydrogenation
作者:Tiziana Benincori、Silvana Bruno、Giuseppe Celentano、Tullio Pilati、Alessandro Ponti、Simona Rizzo、Mara Sada、Francesco Sannicolò
DOI:10.1002/hlca.200590139
日期:2005.7
A process-scale stereoselective synthesis of nature-identical (−)-(S,S)-7-hydroxycalamenal (=(−)-(5S,8S)-5,6,7,8-tetrahydro-3-hydroxy-5-methyl-8-(1-methylethyl)naphthalene-2-carbaldehyde; (−)-1a) in 96% enantiomeric excess (ee) with the aid of chiral Ru complexes has been developed. The key step was the enantioselective hydrogenation of easily accessible 2-(4-methoxyphenyl)-3-methylbut-2-enoic acid
与自然界相同的(-)-(S,S)-7-羟基cal胺(=(-)-(5 S,8 S)-5,6,7,8-四氢-3-羟基借助手性Ru配合物,开发了96%对映异构体过量(ee)的-5-甲基-8-(1-甲基乙基)萘-2-甲醛;(-)- 1a)。关键步骤是将易于获得的2-(4-甲氧基苯基)-3-甲基丁-2-烯酸(10)在86%ee中对映体选择性氢化为(+)- 11(方案5和表1)。通过诱导中间体(+)-3,4-二氢-4-(1-甲基乙基)-7-甲氧基-2的结晶,光学纯度(96%ee)大大提高。H-萘-1-酮((+)- 3)。对类似物(-)- 9进行的计算构象分析合理化了CC键催化加氢中获得的高非对映选择性。