| 摘要 |
<p>Prepn. of cyclohex-2-en-1-ones having formula (I) (where R1 and R2 each is satd. 1-20C hydrocarbyl or Ph or R1 and R2 are linked to form a 5- or 6-membered cycloalkyl gp. R3 and R4 may be H or non-linked R1 and R2-type gps.). Prepn. comprises hydroformylating a ketone having formula (II), using Rh catalysts, and dehydrating the obtd. formyl derivs., (III), under acid conditions, with ring-closure. (I) are odoriferous materials with a wide range of wood-notes. (I) can also be used as intermediates in prepn. of mono-, sesqui- and diterpenes. E.g. 4-isopropyl-cyclohex-2-en-1-one can be converted to menth-2-en-1-ol, followed by allyl rearrangement and hydrogenation to d,1-menthol. In an example, 4-isopropyl-cyclohex-2-en-1-one was prepd. by (i) hydroformylation of 6-methyl-hept-5-en-2-one to 5-formyl-6-methyl-heptan-2-one and (ii) dehydration and ring-closure with H3PO4.</p> |
