40391-19-3Relevant academic research and scientific papers
The formation of 7-oxabicyclo[4.2.0]octanes and 6-oxabicyclo[3.2.1]octanes via cationic iodocyclization
Nichols, Christopher J.
, p. 2167 - 2179 (2007/10/03)
Several 2-cyclohexenemethanol derivatives were subjected to cationic iodocyclization. Two product types were formed: the fused 7-oxabicyclo[4.2.0]octane, and the bridged 6-oxabicyclo[3.2.1]octane. The degree of substitution in the alkenol determined the ratio of the products, with aromatic substituents leading to the formation of the fused system as the major product.
Formation of homoallyl alcohols and 4-chlorotetrahydropyrans from allyl-stannanes, aldehydes and TiCl4 or Cp2TiCl2
Marton, Daniele,Tagliavini, Giuseppe,Zordan, Michele,Wardell, James L.
, p. 295 - 305 (2007/10/02)
Reaction between Bu3SnCHR1CH=CHR2 (1; R1 = H, R2 = H or Me; R1, R2 = (CH2)3) and EtCHO in the presence of TiCl4 or Cp2TiCl2 are reported.The compound, Cp2TiCl2, has been found to be an effective Lewis acid catalyst for the allylation of EtCHO using 1 (R1 = H, R2 = Me) and 1 (R1, R2 = (CH2)3) in CH2Cl2 or Et2O solutions at -78 deg C; the products after hydrolysis are homoallyl alcohols with stereo- and regio-selectivities different from those found for TiCl4- reactions.Reactions with an excess of EtCHO in the presence of TiCl4 give 4-Cl-3-R1-5-R2-2,6-2Et-tetrahydropyrans (2) via insertions of a second EtCHO into the metal-O bond of the initially produced homoallyl alcoholate: the trans-2 compounds are obtained from threo-EtCH(OM')CHR2CH=CHR1 and cis-2 from erythro-EtCH(OM')CHR2CH=CHR1 (e.g., M' = TiCl3).
Hydrated ?-bonded organometallic cations in organic synthesis. I. Allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, and cinnamyl-stannation of carbonyl compounds in water
Furlani, Donatella,Marton, Daniele,Tagliavini, Giuseppe,Zordan, Michele
, p. 345 - 356 (2007/10/02)
Homoallylic alcohols can be prepared in water by allyl-, crotyl-, 1-methylallyl-, cyclohex-2-enyl-, or cinnamyl-stannation of such carbonyl compounds as aldehydes, dialdehydes, and ketones, as well as acetals.The procedure is based on: Bu2RSnCl + R'COR" + (1/2)H2O -> R(HO)CR'R" + (1/2)(Bu2SnCl)2O where R = allyl, crotyl, 1-methylallyl, cyclohex-2-enyl, or cinnamyl group, R' = H or alkyl group, R" R'= alkyl group.In most cases, the reaction products are obtained rapidly in high yields (80-100percent).Hydrated organometallic cations Bu2RSn+(aq) are partly involved.These results, together with those already published on 2-propynyl-and allenyl-stannation, indicate the value of this procedure.
Synthesis with Organoboranes; 4. Transformation of Olefins into Homoallylic Alcohols, β,γ- and α,β-Unsaturated Ketones via Allylic Diethylboranes
Zaidlewicz, Marek
, p. 701 - 703 (2007/10/02)
Allylic diethylboranes are obtained from 1-methylcycloalkenes and 2-alkenes, respectively, via metalation with trimethylsilylmethylpotassium (generated in situ from bis(trimethylsilylmethyl)mercury and potassium sand) and subsequent reaction with chlorodiethylborane.The allylic boranes react diastereoselectively with aldehydes to give homoallylic alcohols.The alcohols are oxidized with pyridinium dichromate to β,γ-unsaturated ketones, which in turn are isomerized with aluminum oxide to conjugated ketones.The transformation provides access to 2-methylene-1-acylcycloalkanes, 3-acyl-1-alkenes and 3-acyl-2-alkenes not readily available by Friedel-Crafts acylation of olefins.
Hydroboration. 76. Hydroboration of Cyclic Dienes with Representative Hydroborating Agents
Brown, Herbert C.,Bhat, Krishna S.
, p. 445 - 449 (2007/10/02)
A detailed study was made of the hydroboration of cyclic dienes with representative hydroborating agents: borane-methyl sulfide (BMS), 9-borabicyclononane (9-BBN), disiamylborane (Sia2BH), dibromo-borane-methyl sulfide (Br2BH*SMe2), and dibromoborane (Br2BH). 1,4-Cyclohexadiene essentially undergoes monohydroboration with a stoichiometric amount of the representative hydroborating agents, whereas 1,5-cyclooctadiene gives the dihydroboration product predominantly.The rapid dimerization of 1,3-cyclopentadiene introduces a complication into its hydroboration.However, monomeric cyclopentadiene undergoes hydroboration primarily to the homoallylic derivative with little of the desired allylic product.Hydroboration of 1,3-cyclohexadiene with a stoichiometric amount of the hydroborating agent furnishes mainly the allylboranes, which upon treatment with acetaldehyde followed by oxidation, furnishes 1-(2-cyclohexenyl)-1-ethanol in good yield.Similary, hydroboration of 1,3-cycloheptadiene and 1,3-cyclooctadiene furnished dihydroborated products preferentially, with lower yields of the corresponding allylboranes, characterized as 1-(2-cycloheptenyl)-1-ethanol and 1-(2-cyclooctenyl)-1-ethanol, respectively, following reaction with acetaldehyde.
Stereochemical Aspects of Aldehyde Additions to Cyclohex-2-enylstannanes
Young, David,Kitching, William
, p. 1767 - 1777 (2007/10/02)
Cyclohex-2-enylation of aldehydes, mediated with boron trifluoride etherate, involves γ-equatorial approach of the presumed aldehyde-Lewis acid adduct (RCHO-BF3), irrespective of starting stannane stereochemistry.Marginal threo selectivity characterizes homoallyl alcohol formation from benzaldehyde, whereas alkanals react with high erythro selectivity, so that 1-(1'-hydroxyalkyl)cyclohex-2-enes in this diastereomeric form are available based on allyltin chemistry.
