Construction of Multiple, Contiguous Quaternary Stereocenters in Acyclic Molecules by Lithiation-Borylation
作者:Charlotte G. Watson、Angelica Balanta、Tim G. Elford、Stéphanie Essafi、Jeremy N. Harvey、Varinder K. Aggarwal
DOI:10.1021/ja509029h
日期:2014.12.17
construction of two quaternary centers, this methodology fails. Instead, using mixed boranes (tBuBMe2), the synthesis of adjacent quaternary stereogeniccenters with full stereocontrol was successful. The process can be repeated two or three times in onepot leading to carbon chains bearing multiple contiguous quaternary stereogeniccenters. The boranes were converted into tertiary alcohols or C-tertiary amines
氨基甲酸酯锂化和硼酸化为硼试剂的同系化提供了一种强有力的方法。然而,当应用于受阻系统(带有 tBu-硼酸酯的二级氨基甲酸酯)以构建两个四元中心时,这种方法失败了。相反,使用混合硼烷 (tBuBMe2),具有完全立体控制的相邻四元立体中心的合成是成功的。该过程可以在一锅中重复两到三次,从而产生带有多个连续四元立体中心的碳链。使用氯胺将硼烷转化为叔醇或 C-叔胺。通过计算确定烷基对 Me 基团迁移的高选择性的起源。
Stereospecific conversion of alcohols into pinacol boronic esters using lithiation–borylation methodology with pinacolborane
作者:Stefan Roesner、Christopher A. Brown、Maziar Mohiti、Alexander P. Pulis、Ramesh Rasappan、Daniel J. Blair、Stéphanie Essafi、Daniele Leonori、Varinder K. Aggarwal
DOI:10.1039/c4cc00993b
日期:——
The synthesis of primary and secondary pinacol boronic esters via lithiation–borylation of carbamates and benzoates with pinacolborane is described.
Alkynyl Moiety for Triggering 1,2‐Metallate Shifts: Enantiospecific sp
<sup>2</sup>
–sp
<sup>3</sup>
Coupling of Boronic Esters with
<i>p</i>
‐Arylacetylenes
作者:Venkataraman Ganesh、Marcin Odachowski、Varinder K. Aggarwal
DOI:10.1002/anie.201703894
日期:2017.8.7
The enantiospecific coupling of secondary and tertiary boronic esters to aromatics has been investigated. Using p-lithiated phenylacetylenes and a range of boronic esters coupling has been achieved by the addition of N-bromosuccinimide (NBS). The alkyne functionality of the intermediate boronate complex reacts with NBS triggering the 1,2-migration of the group on boron to carbon giving a dearomatized
Asymmetric Synthesis of Tertiary Alcohols and Thiols via Nonstabilized Tertiary α-Oxy- and α-Thio-Substituted Organolithium Species
作者:Alexander P. Pulis、Ana Varela、Cinzia Citti、Pradip Songara、Daniele Leonori、Varinder K. Aggarwal
DOI:10.1002/anie.201706722
日期:2017.8.28
Nonstabilized α-O-substituted tertiary organolithium species are difficult to generate, and the α-S-substituted analogues are configurationally unstable. We now report that they can both be generated easily and trapped with a range of electrophiles with high enantioselectivity, providing ready access to a range of enantioenriched tertiary alcohols and thiols. The configurational stability of the α-S-organolithium