“…In contrast to styrene, 1-heptene, and some other alkenes when added to the reaction mixture did not undergo rapid enough ligand exchange with the parent titanacyclopropane intermediate 46 in the presence of only catalytic quantities of Ti(O i -Pr) 4 to afford the corresponding 1,2-disubstituted cyclopropanols in satisfactory yields. Sato et al as well as Cha et al ,, independently found that upon treatment of esters with an excess of an organomagnesium compound in the presence of close to equimolar amounts of titanium tetraisopropoxide as well as 1 equiv of various terminal alkenes, 1,2-disubstituted cyclopropanols bearing substituents from the respective alkene are obtained in moderate to good yields (Scheme and Table ). − The best results have been achieved using isopropyl-, butyl-, cyclopentyl-, or cyclohexylmagnesium halides. ,, 32 …”
“…In contrast to styrene, 1-heptene, and some other alkenes when added to the reaction mixture did not undergo rapid enough ligand exchange with the parent titanacyclopropane intermediate 46 in the presence of only catalytic quantities of Ti(O i -Pr) 4 to afford the corresponding 1,2-disubstituted cyclopropanols in satisfactory yields. Sato et al as well as Cha et al ,, independently found that upon treatment of esters with an excess of an organomagnesium compound in the presence of close to equimolar amounts of titanium tetraisopropoxide as well as 1 equiv of various terminal alkenes, 1,2-disubstituted cyclopropanols bearing substituents from the respective alkene are obtained in moderate to good yields (Scheme and Table ). − The best results have been achieved using isopropyl-, butyl-, cyclopentyl-, or cyclohexylmagnesium halides. ,, 32 …”
“…In 1999 Kulinkovich and co‐workers described a new synthesis of ipsenol ( I ) and ipsdienol ( II ) [50] starting with 2‐(2,2‐diethoxyethyl)‐1‐methyl‐1‐cyclopropanol ( 33 ), prepared by reaction of n ‐BuMgBr/Et 2 O with a mixture of vinylacetic aldehyde diethyl acetal, and ethyl acetate, in the presence of Ti(O‐ i ‐Pr) 4 . As shown in Scheme 14, the regioselective two‐step sequence of bromination‐dehydrobromination of compound 33 afforded 3‐(2,2‐diethoxyethyl)‐3‐buten‐2‐one ( 34 ) in 91 % yield.…”
Section: Synthesis Of (±)‐Ipsenol and (±)‐Ipsdienolmentioning
confidence: 99%
“…Final acid hydrolysis afforded 3‐methylenepent‐4‐enal ( 21 ) that, without purification, was reacted with i BuMgBr in ethyl ether. at 0 °C, or with 2‐methyl‐1‐propenylmagnesium bromide in THF, at −15 °C, to give ipsenol ( I ) and ipsdienol ( II ) in 52 and 44 % yields, respectively, from intermediate 35 [50] …”
Section: Synthesis Of (±)‐Ipsenol and (±)‐Ipsdienolmentioning
Herein I present a review on the synthesis of ipsenol and ipsdienol, two aggregation pheromones of bark beetles, isolated from different species of genus Ips, and serious pests of conifer forests. I have covered the literature for around fifty years, since 1968 to 2020. This account has been divided in different sections and sub‐sections, including a general and brief outlook on their isolation, structure and biological activity, to continue with the reported synthesis of racemic ipsenol and ipsdienol, including my own contribution to topic, and the presentation of reports describing the synthesis of enantiomerically pure ipsenol and ipsdienol. Particular attention has been devoted to identify and highlight racemic or enantiomerically pure “isoprene synthons”, and isoprenylation methods employed in the synthesis of ipsenol and ipsdienol, of general interest for related terpene derivatives synthesis.
“…A year later, Kulinkovich et al 30 reported the synthesis of the ips bark beetle pheromones amitinol 31, (±)-ipsdienol 32 and (±)-ipsenol 33 using previously established methodology. The common key intermediate 30 used for the synthesis of all three target compounds was prepared using a Kulinkovich cyclopropanation-ring opening strategy (Scheme 12).…”
The Kulinkovich cyclopropanation reaction provides a flexible and convenient method for the synthesis of cyclopropanols. Together with the diverse chemistry of the cyclopropanol unit, it offers access to a wide range of functionalised unsaturated and saturated compounds. The successful use in the synthesis of natural compounds is outlined in this perspective.
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