694-25-7Relevant academic research and scientific papers
Hydrophosphination of Bicyclo[1.1.0]butane-1-carbonitriles
Milligan, John A.,Busacca, Carl A.,Senanayake, Chris H.,Wipf, Peter
, p. 4300 - 4303 (2016/10/30)
Hydrophosphination of bicyclo[1.1.0]butyl nitriles with phosphine boranes and phosphites provided novel cyclobutyl-P derivatives. The reaction generally favors the syn-diastereomer, and the nitrile can be reduced and converted to other functional groups, thus enabling the preparation of bidentate ligands that access new conformational space by virtue of their attachment to the torsionally malleable but sterically restrictive cyclobutane scaffold. The enantioselective hydrogenation of dehydrophenylalanine using a bidentate phosphine-phosphite ligand illustrates the synthetic utility of the newly prepared scaffold.
Mechanism and Stereochemistry of General Acid Catalyzed Additions to Bicyclobutane
Hoz, Shmaryahu,Livneh, Mordechai,Cohen, Drora
, p. 4537 - 4544 (2007/10/02)
The electrophilic addition of MeOH across the central bond of 3-X-bicyclobutanecarbonitriles (X = H, Me, Cl) was found to be a general acid catalyzed reaction with Broensted α = 0.96.The ρ+ value of these reactions is -7.1 +/- 1.3.These two coefficients are interpreted as an indication of an unbalanced transition state.In the case of X = H and Me, the addition reaction is of syn stereochemistry.This is probably also the stereochemistry in the case X = Cl.However, the initialy formed adduct in this case reacts further to give ketal 3a.In the presence of NaClO4, anti addition products are also observed and reaction rates increase linearly with the concentration of the salt.Ab initio calculations (3-21G) show that protonated bicyclobutane has two stable geometries (Cs symmetry), one highly puckered and the other nearly planar.The first structure is more stable by 9.5 kcal/mol (6-31G*/3-21G).It is concluded that with strong nucleophiles, the syn stereochemistry results from a concerted attack by proton and the nucleophile from the equatorial directions.With weaker nucleophiles, the first step is protonation of the substrate which is followed by nucleophilic attack on the puckered cation.Both attacks take place from an equatorial direction leading therefore ultimately to the observed stereospecificity.
