Stereocontrolled Fluorobenzylation of Vinyl Sulfones and α,β-Unsaturated Esters Mediated by a Remote Sulfinyl Group. Synthesis of Functionalized Enantiomerically Pure Benzylic Fluorides
摘要:
A sulfinyl group in an ortho position confers enough chemical and configurational stability to monofluorobenzylcarbanions to evolve in a completely stereoselective way in their reactions with beta-substituted vinyl sulfones and alpha,beta-unsaturated esters. Reactions afford easily separable mixtures of two epimers differing in the configuration of the center derived from the Michael acceptor (up to 98% de). They can be easily converted into enantiomerically pure gamma-fluorinated gamma-phenylsulfones and gamma-phenylesters bearing two chiral centers.
Asymmetric Nucleophilic Monofluorobenzylation of Carbonyl Compounds: Synthesis of Enantiopure vic-Fluorohydrins and α-Fluorobenzylketones
作者:Yolanda Arroyo、M. Ascensión Sanz-Tejedor、Alejandro Parra、José Luis García Ruano
DOI:10.1002/chem.201103919
日期:2012.4.23
Asymmetricnucleophilic monofluoroalkylation of a broad range of aldehydes with an α‐fluoro‐γ‐sulfinylbenzyl carbanion takes place with complete control of the facial selectivity at the carbanion and good to high anti‐diastereoselectivity to give easily separable mixtures of two optically pure 1,2‐fluorohydrin derivatives (up to 24:1 anti/syn). Separation and removal of the p‐tolylsulfinyl group with
范围广泛的与α氟γ-sulfinylbenzyl碳负离子醛的不对称亲核monofluoroalkylation发生与负碳离子和良好的高面部选择性的完全控制抗-diastereoselectivity,得到两种旋光纯1,2-易于分离的混合物‐氟代醇衍生物(最多24:1 anti / syn)。用t BuLi分离和除去对甲苯基亚磺酰基可提供对映体纯的抗1,2-二取代-1,2-氟代醇,而α-氟苄基酮可通过混合物的脱亚磺酰化后再进行吡啶鎓氯代铬酸铬的氧化而制得(单锅)。过程)。
Asymmetric Nucleophilic Monofluorobenzylation of Allyl and Propargyl Halides Mediated by a Remote Sulfinyl Group: Synthesis of Homoallylic and Homopropargylic Fluorides
作者:Yolanda Arroyo、M. Ascensión Sanz-Tejedor、Alejandro Parra、Inés Alonso、José Luis García Ruano
DOI:10.1021/jo501096f
日期:2014.8.1
Fluorinated 2(p-tolylsulfinyl)benzyl carbanions react with allyl and propargyl halides in a highly stereoselective way, providing homoallylic and homopropargylic fluorides, respectively, with high optical purity. Theoretical calculations found transition states for these transformations whose relative stabilities are consistent with the experimentally observed stereoselectivity.