1105697-11-7Relevant academic research and scientific papers
Borabicyclo[3.3.2]decanes and the stereoselective asymmetric synthesis of 1,3-diol stereotriads from 1,3-diborylpropenes
Gonzalez, Ana Z.,Roman, Jose G.,Alicea, Eyleen,Canales, Eda,Soderquist, John A.
supporting information; experimental part, p. 1269 - 1273 (2009/06/28)
The synthesis of mixed borabicyclodecane (BBD)-derived 1,3-diborylpropenes (trans-1)is described. These new bimetallic reagents are effective for the selective asymmetric allylboration first of ketones (or ketimines)and second of aldehydes (or aldimines). Formed as a thermodynamic mixtu re of trans regioisomers from cis-1 through a series of 1,3-borotropic shifts, only trans-1 undergoes the monoallylation of ketones. After this single addition, this process is effectively shut down after the reaction of the 10-Ph-9-BBD portion in 1. Serving as a molecular gate, the rearranged 10-TMS-9-BBD trans allylborane intermediate 11 reacts only after an aldehyde (or aldimine) is added. This allylation fixes the last two stereogenic centers of the 2-vinyl-1,3-diol stereotriad, ultimately resulting in 16 (or 1,3-amino alcohols) in 50-72percent yield (>98percent ee)as single observable diastereomers. These reagents 1 uniquely function as the equivalent of 1,1-bimetallic allylic reagents, adding sequentiall y first to ketones and second to aldehydes.
9-Borabicyclo[3.3.2]decanes and the asymmetric hydroboration of 1,1-disubstituted alkenes
Gonzalez, Ana Z.,Roman, Jose G.,Gonzalez, Eduvigis,Martinez, Judith,Medina, Jesus R.,Matos, Karl,Soderquist, John A.
supporting information; experimental part, p. 9218 - 9219 (2009/02/02)
The syntheses of the optically pure asymmetric hydroborating agents 1 (a, R = Ph; b, R = TMS) in both enantiomeric forms are reported. These reagents are effective for the hydroboration of cis-, trans- and trisubstituted alkenes. More significantly, they exhibit unprecedented levels of selectivity in the asymmetric hydroboration of 1,1-disubstituted alkenes (28-92% ee), a previously unanswered challenge in the nearly 50 year history of this reagent-controlled process. For example, the hydroboration of α-methylstyrene with 1a produces the corresponding alcohol 6f in 78% ee (cf., Ipc2BH, 5% ee). Suzuki coupling of the intermediate adducts 5 produces the nonracemic products 7 very effectively (50-84%) without loss of optical purity. Copyright
