Enantiospecific Synthesis of Aniline-Derived Sulfonimidamides

Reaction of sulfonimidoyl fluorides with anilines and Ca(NTf2)2 results in the formation of chiral sulfonimidamides. The reaction proceeds with inversion of the stereocenter at a sulfur atom. Enantiospecificity of the reaction was observed for all studied non-heterocyclic anilines. Combined experimental and computational mechanistic studies highlight chelate-type coordination of the sulfonimidoyl group to Ca(NTf2)2 and the formation of a SN2-like transition state, in which leaving F- coordinates with the Ca2+ ion.

SuFExable polymers with helical structures derived from thionyl tetrafluoride

Sulfur(VI) fluoride exchange (SuFEx) is a category of click chemistry that enables covalent linking of modular units through sulfur(VI) connective hubs. The efficiency of SuFEx and the stability of the resulting bonds have led to polymer chemistry applications. Now, we report the SuFEx click chemistry synthesis of several structurally diverse SOF₄-derived copolymers based on the polymerization of bis(iminosulfur oxydifluorides) and bis(aryl silyl ethers). This polymer class presents two key characteristics. First, the [-N=S(=O)F-O-] polymer backbone linkages are themselves SuFExable and undergo precise SuFEx-based post-modification with phenols or amines to yield branched functional polymers. Second, studies of individual polymer chains of several of these new materials indicate helical polymer structures. The robust nature of SuFEx click chemistry offers the potential for post-polymerization modification, enabling the synthesis of materials with control over composition and conformation.

Enantioselective Construction of 2-Aryl-2,3-dihydrobenzofuran Scaffolds Using Cu/SPDO-Catalyzed [3 + 2] Cycloaddition

A new, efficient approach toward the preparation of 2-aryl-2,3-dihydrobenzofuran scaffolds through the Cu/SPDO-catalyzed [3 + 2] cycloaddition between quinone ester and styrene derivatives has been developed. The procedure features excellent enantioselectivities (up to 99% ee), high yields (up to 96%), and broad substrate tolerance. Additionally, asymmetric synthesis of natural corsifurans A and B from commercially available starting materials has also been achieved in two or three steps using this reaction as a key transformation.

Remote asymmetric conjugate addition catalyzed by a bifunctional spiro-pyrrolidine-derived thiourea catalyst

A novel spiro-pyrrolidine (SPD)-derived bifunctional thiourea catalyst has been developed and used in a stereoselective conjugate addition of furfurals to β,γ-unsaturated α-ketoesters.

The effect of prophylactic rewarming on postoperative nausea and vomiting among patients undergoing laparoscopic hysterectomy: a prospective randomized clinical study

BACKGROUND

Postoperative nausea and vomiting (PONV) is a common complication from general anesthesia that impacts on postoperative recovery.

OBJECTIVE

To evaluate prophylactic rewarming following general anesthesia, so as to decrease the incidence of PONV among patients undergoing laparoscopic hysterectomy.

DESIGN AND SETTING

Prospective randomized clinical study at a hospital in China.

METHODS

Sixty-two patients were randomly assigned into two groups. The forced air warming (FAW) group received pre-warmed Ringer's solution with FAW until the end of surgery. The control group received Ringer's solution without FAW. The pre-warmed Ringer's solution was stored in a cabinet set at 40 °C. The FAW tube was placed beside the patient's shoulder with a temperature of 43 °C.

RESULTS

Sixty patients completed the study. The FAW group showed significant differences versus the controls regarding temperature. At 6, 24 and 48 hours postoperatively, the incidences of PONV were 53.3%, 6.7% and 3.3% in the FAW group versus 63.3%, 30% and 3.3% in the controls. VAS scores were significantly lower in the FAW group than in the controls at 24 hours (P= 0.035). Forty-item questionnaire total scores in the FAW group were significantly higher than in the controls. The physical independence and pain scores at 24 hours and emotional support and pain scores at 48 hours in the FAW group were higher than in the controls (P < 0.05). There was no difference in hemodynamics or demographics between the two groups (P > 0.05).

CONCLUSIONS

Prophylactic rewarming relieved PONV and improved the quality of postoperative recovery.

CHINESE CLINICAL TRIAL REGISTER (CHICTR)

ChiCTR-IOR-17012901.

Catalytic Enantioselective Synthesis and Switchable Chiroptical Property of Inherently Chiral Macrocycles

We report herein a strategy to construct enantiopure inherently chiral macrocycles, ABCD-type heteracalix[4]aromatics, through a catalytic enantioselective intramolecular C-N bond forming reaction. A chiral ligand-palladium complex was found to efficiently induce the inherent chirality of molecules during the macrocyclization process with ee values up to >99%. The resulting ABCD-type heteracalix[4]aromatics displayed excellent and pH-triggered switchable electronic circular dichroism and circularly polarized luminescence properties.

Silicon-Free SuFEx Reactions of Sulfonimidoyl Fluorides: Scope, Enantioselectivity, and Mechanism

SuFEx reactions, in which an S−F moiety reacts with a silyl‐protected phenol, have been developed as powerful click reactions. In the current paper we open up the potential of SuFEx reactions as enantioselective reactions, analyze the role of Si and outline the mechanism of this reaction. As a result, fast, high‐yielding, “Si‐free” and enantiospecific SuFEx reactions of sulfonimidoyl fluorides have been developed, and their mechanism shown, by both experimental and theoretical methods, to yield chiral products.

Topological nature of the node-arc semimetal PtSn4 probed by de Haas-van Alphen quantum oscillations

Dirac node arc semimetal state is a new topological quantum state which is proposed to exist in PtSn₄ (Wu et al 2016 Dirac node arcs in PtSn₄ Nat. Phys. 12 667-71). We present a systematic de Haas-van Alphen quantum oscillation study on this compound. Two intriguing oscillation branches, i.e. F ₁ and F ₂, are detected in the fast Fourier transformation spectra, both of which are characterized to possess tiny effective mass and ultrahigh quantum mobility. And the F ₂ branch exhibits an angle-dependent nontrivial Berry phase. The features are consistent with the existence of the node arc semimetal state and shed new light on its complicated Fermi surfaces and topological nature.

Synthesis and Structure of Functionalized Homo Heteracalix[2]arene[2]triazines: Effect of All Heteroatom Bridges on Macrocyclic Conformation

A number of unprecedented homo heteracalix[2]arene[2]triazines were synthesized by means of a fragment coupling approach. Two directional nucleophilic substitution reactions of N-Boc-protected 1,3-dihydrazobenzene with cyanuric acid chloride and 2-butoxy-4,6-dichloro-1,3,5-triazine led to hydrazo-linked trimers, which underwent an efficient macrocyclic condensation reaction with functionalized resorcinol derivatives to afford (NHNBoc)₂,O₂-calix[2]arene[2]triazine macrocycles, which contain a functional group either on the upper rim or the lower rim. The use of 1,3-phenylenediamines instead of resorcinol in the reaction produced (NR)₂,(NHNBoc)₂-calix[2]arene[2]triazines. Postmacrocyclization modifications such as a nucleophilic substitution reaction of chloro on triazine by amines and the removal of Boc from hydrazo moieties produced homo calix[2]arene[2]triazine derivatives. In the solid state, (NHNR)₂,O₂-bridged calix[2]arene[2]triazines with and without a substituent on the upper rim position and (NMe)₂,(NHNBoc)₂-calix[2]arene[2]triazine adopted a typical partial cone conformation while the heavily twisted 1,3-alternate conformational structures were observed for both (NHNBoc)₂,O₂-calix[2]arene[2]triazines bearing a functional group on the lower rim position and (NH)₂,(NHNBoc)₂-calix[2]arene[2]triazine. In solution, all synthesized homo heteracalix[2]arene[2]triazines existed as the mixture of different macrocyclic conformers, which underwent slow interconversions at room temperature relative to the NMR time scale.

Synthesis and conformational structure of hydrazo-bridged homo calix[2]pyridine[2]triazines

Presented in this paper are the practical synthesis and conformational structure of hydrazo-bridged homo calix[4]arenes.

Overexpression of an alternative oxidase gene, OsAOX1a, improves cold tolerance in Oryza sativa L

Low temperature is a major environmental stress in rice cultivating and production. The alternative oxidase 1 (AOX1) gene is potentially important for genetic engineering to increase cold adaptation. However, previous studies related to this effect have mostly focused on the dicot plants Arabidopsis and tobacco, whereas functional research on rice is limited. In this study, we cloned a rice predominant cold-response AOX1 gene, OsAOX1a. Transgenic rice plants with overexpression of OsAOX1a were obtained. We found that OsAOX1a overexpression could strongly enhance the cold growth of seedlings, especially with respect to root extension. However, growth between transgenic and control plants did not differ under normal conditions. Furthermore, the lipid peroxidation and ion leakage rate were determined after cold treatment in transgenic plants. Both factors were reduced by OsAOX1a overexpression, which revealed that OsAOX1a could reduce oxidative damage under cold stress. Taken together, our results suggested that overexpressing OsAOX1a could improve growth performance of rice under cold stress, which might be closely related to the reduction of reactive oxygen species generation and oxidative damage.

[Effects of nimodipine on rabbits with symptomatic cerebral vasospasm]

OBJECTIVE

To investigate the effects of nimodipine on symptomatic cerebral vasospasm in rabbits.

METHODS

Twenty four japanese white rabbits which ligation of bilateral common carotid arteries and no neurological deficits were randomized to sham-operation, subarachnoid hemorrhage (SAH) and nimodipine which injected of nimodipine 0.1 mg/kg, continuous vein administration 5 day. The behavior scores, neurological scores were observed everyday and cerebral angiography changes were measured twice by 3D-CTA, and basilar artery was removed for pathological examination after last CTA examination.

RESULTS

In SAH group, The basilar artery were significantly vasoconstrictive on 5 days, neurological scores were increased, and the basilar artery was found apoptosis-like changes under light microscopic and electron microscope. Nimodipine group could not dilated the basilar artery arteriospasm after SAH, but it could attenuate neurological deficit, and obviously alleviate the pathological changes of basilar artery.

CONCLUSION

Nimodipine could not vasodilation of basilar artery in SCVS, but obviously could alleviate neurological changes and pathological changes of basilar artery in rabbits with symptomatic cerebral vasospasm.

Unique histological features of the left atrial posterior wall

The left atrial posterior wall (LAPW) plays a critical role in atrial fibrillation, but the underlying mechanism remains unclear. In the present study, we sought to characterize the histological features of the LAPW. Different atrial regions were dissected from hearts of normal Sprague-Dawley rats and humans. Haematoxylin/eosin and van Gieson staining were used to analyse atrial cardiomyocyte arrangement and collagen distribution, respectively. Intercellular junctions were evaluated by transmission electron microscopy. In contrast with other atrial regions, the LAPW exhibited more disorganized cardiomyocytes, larger intercellular spaces and variable myocardial fibre arrangement. The proportion of collagen was significantly higher in the LAPW than in other atrial regions. Interestingly, desmosomes were sparse along with intercellular gaps in the LAPW. In summary, distinct disarrangement of cardiomyocytes and an abundance of collagen exist in the LAPW. The sparsity of desmosomes in the LAPW may be related to the heterogeneous distribution and separation of atrial myocytes.