Direct Reductive Cyanation of A 2-Pyrrolidinone Chiral Building Block Bearing An Unprotected Hydroxyl Group: A Stereoselective Synthesis of N-Methyl-2-epi-bulgecinine

报道手性合成砌块(4S,5R)-N-芐氧基-5-羟甲基-2-吡咯烷酮(3a)的直接还原氰基化及产物的立体化学与转化研究.含未保护羟基的内酰胺用L; iAlH_4/KCN体系直接还原氰基化,生成比例为69:; 31的2,5-反式/顺式非对映立体异构体.与文献类似结果对比显示,氰基负离子对5-羟甲基-△-1-吡咯啉鎗中间体的加成主要受立体电子效应和C(5; )位取代基(羟甲基)与进攻试剂间烯丙型1,3-位阻控制.该混合物在碱性条件下水解,生成比例为10:; 90的2,5-反式/2,5-顺式-bulgecinine衍生物.这一结果表明氰基水解反应伴随着在C(2)位发生了有合成价值的串联差向异构化.由此; 建立了立体选择性地合成2,5-顺式(-)-N-甲基-2-别-bulgecinine的简便方法.The direct reductive cyanation of N-benzyl-4-benzyloxy-5-hydroxymethyl-2-pyrrolidinone (3a), a lactam bearing a free hydroxyl group, has been achieved with the LiAlH4/KCN combination. The reaction afforded 2,5-trans-2-cyano-5hydroxylmethyl-4-benzyloxy-pyrrolidine (5a) and its cis-diastereomer 5b in a ratio of 69: 31 with a combined yield of 63%. The observed 2,5-trans-stereoselectivity is suggested to be resulted from both stereoelectronic effect and allylic 1,3-strain between the hydroxymethyl group at C(5) and the incoming cyanide anion on the presumed Delta-1 pyrrolinium ion intermediate. The subsequent hydrolysis of the cyano group of the diastereomeric mixture 5a/5b (trans: cis=69: 31) under basic conditions afforded the corresponding 5-hydroxymethyl-4-benzyloxyproline with 2,5-cis-diastereomer as the major diastereomer (trans: cis= 10: 90). This result implies that a synthetically useful epimerization at C(2) has occurred concomitantly. This unexpected result afforded a concise and highly stereoselective synthesis of 2,5-cis-(-)-N-methyl-2-epi-bulgecinine.National Natural Science Foundation of China [21332007]; Program for; Changjiang Scholars and Innovative Research Team in University of; Ministry of Educatio

Amplitude analysis of the decays D0 → π+π−π+π− and D0 → π+π−π0π0*

Using e+e− annihilation data corresponding to an integrated luminosity of 2.93 fb−1 taken at the center-of-mass energy √s = 3.773 GeV with the BESIII detector, a joint amplitude analysis is performed on the decays D0 → π+π−π+π− and D0 → π+π−π0π0 (non-η). The fit fractions of individual components are obtained, and large interferences among the dominant components of the decays D0 → a1(1260)π, D0 → π(1300)π, D0 → ρ(770)ρ(770), and D0 → 2(ππ)S are observed in both channels. With the obtained amplitude model, the CP-even fractions of D0 → π+π−π+π− and D0 → π+π−π0π0 (non-η) are determined to be (75.2 ± 1.1stat. ± 1.5syst.) % and (68.9 ± 1.5stat. ± 2.4syst.)%, respectively. The branching fractions of D0 → π+π−π+π− and D0 → π+π−π0π0 (non-η) are measured to be (0.688 ± 0.010stat. ± 0.010syst.)% and (0.951 ± 0.025stat. ± 0.021syst.)%, respectively. The amplitude analysis provides an important model for the binning strategy in measuring the strong phase parameters of D0 → 4π when used to determine the CKM angle γ(φ3) via the B− → DK− decay

Measurement of integrated luminosity of data collected at 3.773 GeV by BESIII from 2021 to 2024

We present a measurement of the integrated luminosity e+e- of collision data collected by the BESIII detector at the BEPCII collider at a center-of-mass energy of Ecm = 3.773 GeV. The integrated luminosities of the datasets taken from December 2021 to June 2022, from November 2022 to June 2023, and from October 2023 to February 2024 were determined to be 4.995±0.019 fb-1, 8.157±0.031 fb-1, and 4.191±0.016 fb-1, respectively, by analyzing large angle Bhabha scattering events. The uncertainties are dominated by systematic effects, and the statistical uncertainties are negligible. Our results provide essential input for future analyses and precision measurements

Determination of the number of ψ(3686) events taken at BESIII

The number of ψ(3686) events collected by the BESIII detector during the 2021 run period is determined to be (2259.3±11.1)×106 by counting inclusive ψ(3686) hadronic events. The uncertainty is systematic and the statistical uncertainty is negligible. Meanwhile, the numbers of ψ(3686) events collected during the 2009 and 2012 run periods are updated to be (107.7±0.6)×106 and (345.4±2.6)×106, respectively. Both numbers are consistent with the previous measurements within one standard deviation. The total number of ψ(3686) events in the three data samples is (2712.4±14.3)×10^