B-allenyl- and B-(gamma-trimethylsilylpropargyl)-10-phenyl-9-borabicyclo[3.3.2]decanes: asymmetric synthesis of propargyl and alpha-allenyl 3-degree-carbinols from ketones.
Simple and efficient Grignard procedures are reported for the syntheses of B-allenyl-10-(phenyl)-9-borabicyclo[3.3.2]decane (1) and its B-(gamma-trimethylsilylpropargyl) counterpart (2) in both enantiomeric forms. Both add selectively to ketones, providing propargyl- and alpha-silylallenyl 3-degree-carbinols, respectively (i.e., 6 (61-93% ee) and 9 (64-98% ee)). The air-stable boron byproduct is efficiently recovered and recycled back to either 1 or 2. The ozonolysis and bromination of 9 provide nonracemic alpha-hydroxy acids and gamma-bromopropynyl carbinols, respectively.
Hernandez
Eliud
E
University of Puerto Rico, Department of Chemistry, Rio Piedras, PR 00931-3346, USA.
Burgos
Carlos H
CH
Alicea
Eyleen
E
Soderquist
John A
JA
D000473:Alkanes / Q000737:chemistry; D000480:Alkynes / Q000138:chemical synthesis*; D002384:Catalysis; D007659:Ketones / Q000737:chemistry*; D000432:Methanol / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D015394:Molecular Structure; D020005:Propanols / Q000138:chemical synthesis*; D013237:Stereoisomerism; D014297:Trimethylsilyl Compounds / Q000737:chemistry*
D000473:Alkanes; D000480:Alkynes; D007659:Ketones; D020005:Propanols; D014297:Trimethylsilyl Compounds; C028255:propargyl alcohol; D000432:Methanol