Concise synthesis of optically active ring-A substituted tryptophans
作者:Chunrong Ma、Xiaoxiang Liu、Shu Yu、Shuo Zhao、James M. Cook
DOI:10.1016/s0040-4039(98)02497-6
日期:1999.1
A concise synthesis of optically active trytophan derivatives was developed via diastereoselective alkylation of the Schöllkopfchiralauxiliary 4 to provide alkyne 2 which underwent palladium-catalyzedheteroannulation with iodoanilines 1 to furnish protected tryptophans 3. Hydrolysis and subsequent saponification of 3 provided the desired tryptophans 12 in good yields.
Regio- and diastereoselective reactions of chiral secondary alkylcopper reagents with propargylic phosphates: preparation of chiral allenes
作者:Juri Skotnitzki、Alexander Kremsmair、Daniel Keefer、Franziska Schüppel、Brieuc Le Cacher de Bonneville、Regina de Vivie-Riedle、Paul Knochel
DOI:10.1039/c9sc05982b
日期:——
SN2′-substitution of secondary alkylcopper reagents with propargylic phosphates enables the preparation of stereodefined alkylallenes. By using enantiomerically enriched alkylcopper reagents and enantioenriched propargylic phosphates as electrophiles anti-SN2′-substitutions were performend leading to α-chiral allenes in good yields with excellent regioselectivity and retention of configuration. DFT-calculations
仲烷基铜试剂与炔丙基磷酸酯的非对映选择性S N 2'取代使得能够制备立体确定的烷基亚烷基。通过使用对映体富集的烷基铜试剂和对映体富集的炔丙基磷酸酯作为亲电子试剂,抗-S N 2'取代反应以高收率产生α-手性烯丙基,具有出色的区域选择性和构型保留。进行DFT计算以合理化这些烷基铜试剂在各种溶剂中的结构,强调它们在THF中的构型稳定性。
Asymmetric synthesis of α-chiral β-hydroxy allenes: copper-catalyzed γ-selective borylative coupling of vinyl arenes and propargyl phosphates
作者:Jung Tae Han、Jaesook Yun
DOI:10.1039/c9cc04165f
日期:——
enantioselective coupling of vinyl arenes with bis(pinacolato)diboron (B2pin2) and propargylic phosphates is presented. The protocol affords a facileroute to enantioenriched α-branched allenes with a versatile pinacolboronate group at the β-position with high enantioselectivity up to 98 : 2 er. In the presence of a copper catalyst complexed with a chiral bisphosphine ligand, catalytic assembly of α-chiral β-hydroxy
Efficient Asymmetric Synthesis of Biologically Important Tryptophan Analogues via a Palladium-Mediated Heteroannulation Reaction
作者:Chunrong Ma、Xiaoxiang Liu、Xiaoyan Li、Judith Flippen-Anderson、Shu Yu、James M. Cook
DOI:10.1021/jo001679s
日期:2001.6.1
A novel and concise synthesis of optically active tryptophan derivatives was developed via a palladium-catalyzed heteroannulation reaction of substituted o-iodoanilines with an internal alkyne. The required internal alkyne 14a or 25 was prepared in greater than 96% de via alkylation of the Schöllkopf chiral auxiliary 19 employing diphenyl phosphate as the leaving group. The Schöllkopf chiral auxiliary