Design, Synthesis and Structure-Odor Correlation of Novel Spiro[4.5]-decan-2-ones
作者:Philip Kraft、Riccardo Cadalbert
DOI:10.1055/s-2002-34847
日期:——
Dehydration and Rupe rearrangement of 2-(3,3-dimethylcyclohexyl)hex-3-yne-2,5-diol (9) furnished as a 3% byproduct the intense vetiver-like smelling 4,7,7-trimethyl-1-methylenespiro[4.5]decan-2-one (11). Motivated by the commercial importance of vetiver oil and the lack of synthetic substitutes as well as the lack of insight into the structural requirements for vetiver odorants, an efficient synthetic route to vetiver-like smelling compounds was developed. It consists of Wittig-Horner-Emmons reaction of diverse cycloalkanones with triethyl 2-phosphonopropionate, subsequent Grignard reaction with in situ conversion to the trienolate, and classical Nazarov cyclization of the resulting dienones. This route not only leads to 11 in 61% yield in the final Nazarov cyclization, but also to 16 analogs, which provide insight into both, the Nazarov reaction and the structure-odor relationship of vetiver odorants. Other vetiver-like smelling compounds discovered include (1RS,4SR,5SR)-1,4,7,7-tetramethylspiro[4.5]decan-2-one (16), 4-methyl-1-methylenespiro[4.6]undecan-2-one (30) and 4-methyl-1-methylenespiro[4.7]dodecan-2-one (31).
脱水和鲁佩重排反应生成的2-(3,3-二甲基环己基)己-3-炔-2,5-二醇(9)以3%的副产物获得了具有强烈的香根草气味的4,7,7-三甲基-1-亚甲基螺[4.5]十烷-2-酮(11)。鉴于香根草油的商业重要性、缺乏合成替代品以及对香根草气味成分结构要求的不足之处,开发了一条有效的合成香根草气味化合物的路线。该路线包括将多种环烷酮与三乙基2-膦丙酸酯进行威蒂格-霍纳-埃蒙斯反应,随后进行格林纳德反应并原位转化为三烯醇盐,最终进行经典的纳扎罗夫环化反应。该合成路线不仅在最后的纳扎罗夫环化中以61%的产率得到化合物11,还得到16种类似物,为纳扎罗夫反应及香根草气味成分的结构-气味关系提供了见解。其他发现的具有香根草气味的化合物包括(1RS,4SR,5SR)-1,4,7,7-四甲基螺[4.5]十烷-2-酮(16)、4-甲基-1-亚甲基螺[4.6]十一烷-2-酮(30)以及4-甲基-1-亚甲基螺[4.7]十二烷-2-酮(31)。