Efficient Synthesis of Enantiomerically Pure C2-Symmetric Diols via the Allylboration of Appropriate Dialdehydes
作者:P.Veeraraghavan Ramachandran、Guang-Ming Chen、Herbert C. Brown*
DOI:10.1016/s0040-4039(97)00414-0
日期:1997.4
The reaction of the enantiomers of B-allyidiisopinocampheylborane with 1,2-, 1,3-, and 1,4-benzenedialdehydes, 2,6-pyridinedicarboxaldehyde, glyoxal, and glutaric dialdehyde, provides the corresponding enantiomers of the bis-homoallylic alcohols in 88-98% de, and greater than or equal to 98% ee. (C) 1997 Elsevier Science Ltd.
Chiral Synthesis via Organoboranes. 46. An Efficient Preparation of Chiral Pyridino- and Thiopheno-18-crown-6 Ligands from Enantiomerically Pure <i>C</i><sub>2</sub>-Symmetric Pyridine- and Thiophenediols<sup>1</sup>
作者:Guang-Ming Chen、Herbert C. Brown、P. Veeraraghavan Ramachandran
DOI:10.1021/jo980899r
日期:1999.2.1
high de and ee. Asymmetric allylboration of 2,6-pyridinedicarboxaldehyde and 2,5-thiophenedicarboxaldehyde provides the corresponding bis-homoallylic alcohols in very high de and ee. These optically pure diols were converted to the disodium or dipotassium salts and treated with tetra(ethylene glycol) ditosylate to obtain the corresponding chiral pyridino and thiopheno-18-crown-6 ligands. However, the