Synthesis and biological activities of novel 5-substituted-1,3,4-oxadiazole Mannich bases and bis-Mannich bases as ketol-acid reductoisomerase inhibitors.

A series of novel 5-substituted-1,3,4-oxadiazole Mannich bases and bis-Mannich bases have been conveniently synthesized in good yields. Their structures were characterized by IR, (1)H NMR, (13)C NMR and elemental analysis. The preliminary bioassay results indicated that some of the compounds showed promising in vitro fungicidal activities towards several test plant fungi; some of them exhibited significant herbicidal activities against Brassica campestris and excellent in vitro inhibitory activities against rice ketol-acid reductoisomerase (KARI). Among 14 novel compounds, 8c, 8d and 8m showed potent KARI inhibitory activities with Ki value of (0.96±0.42), (3.86±0.49) and (3.10±0.71) µmol/L, respectively, and were comparable with IpOHA. These compounds could be novel KARI inhibitors for further investigation. The density functional theory (DFT) calculations and molecular docking were carried out to study the structure-activity relationship (SAR) of the active inhibitors in this Letter.

Rapid access to t-butylalkylated olefins enabled by Ni-catalyzed intermolecular regio- and trans-selective cross-electrophile t-butylalkylation of alkynes.

Among the carbo-difunctionalization of alkynes, the stereoselective dialkylation of alkynes is the most challenging transformation due to associated competitive side reactions and thus remains underdeveloped. Herein, we report the first Ni-catalyzed regio- and trans-selective cross-dialkylation of alkynes with two distinct alkyl bromides to afford olefins with two aliphatic substituents. The reductive conditions circumvent the use of organometallic reagents, enabling the cross-dialkylation process to occur at room temperature from two different alkyl bromides. This operationally simple protocol provides a straightforward and practical access to a wide range of stereodefined dialkylated olefins with broad functional group tolerance from easily available starting materials.

Ni-catalyzed regio- and stereo-defined intermolecular cross-electrophile dialkylation of alkynes without directing group.

The development of straightforward synthesis of regio- and stereodefined alkenes with multiple aliphatic substituents under mild conditions is an unmet challenge owing to competitive ß-hydride elimination and selectivity issues. Herein, we report the nickel-catalyzed intermolecular cross-dialkylation of alkynes devoid of directing or activating groups to afford multiple aliphatic substituted alkenes in a syn-selective fashion at room temperature. The combination of two-electron oxidative cyclometallation and single-electron cross-electrophile coupling of nickel enables the syn-cross-dialkylation of alkynes at room temperature. This reductive protocol enables the sequential installation of two different alkyl substituents onto alkynes in a regio- and stereo-selective manner, circumventing the tedious preformation of sensitive organometallic reagents. The synthetic utility of this protocol is demonstrated by efficient synthesis of multi-substituted unfunctionalized alkenes and diverse transformations of the product.

Access to Z-Selective 1,3-Enynes via Ni-Catalyzed Intermolecular Cross-Alkylalkynylation of Terminal Alkynes.

Access to 1,3-conjugated enynes with defined stereoselectivity is highly desirable and challenging. Herein, we report a facile synthesis of stereodefined 1,3-conjugated enynes via Ni-catalyzed intermolecular cross-alkylalkynylation of alkynes with unsaturated carbonyl compounds and alkynes or alkynyl silicates. The operational simple protocol proceeds at room temperature and tolerates a wide range of functional groups, providing an attractive alternative to carbonyl-tethered trisubstituted conjugated 1,3-enynes from easily accessible starting materials.

Effects of omitting elective neck irradiation to nodal Level IB in nasopharyngeal carcinoma patients with negative Level IB lymph nodes treated by intensity-modulated radiotherapy: a Phase 2 study.

OBJECTIVE: To investigate the need for elective neck irradiation (ENI) to nodal Level IB in patients with nasopharyngeal carcinoma (NPC) with negative Level IB lymph nodes (IB-negative) treated by intensity-modulated radiotherapy (IMRT). METHODS: We conducted a Phase 2 prospective study in 123 newly diagnosed IB-negative patients with NPC treated by IMRT, who met at least 1 of the following criteria: (1) unilateral or bilateral Level II involvement with 1 of the following: Level IIA involvement or any Level II node ≥2 cm/with extracapsular spread; (2) ≥2 unilateral node-positive regions. Bilateral Level IB nodes were not contoured as part of the treatment target and treated electively. Level IB regional recurrence rate; pattern of treatment failure; 3-year overall survival (3y-OS), 3-year local control (3y-LC) and 3-year regional control (3y-RC) rates; toxicities; and dosimetric data for planning target volumes, organs at risk, Level IB and submandibular glands (SMGs) were evaluated. RESULTS: Two patients developed failures at Level IB (1.6%). The 3y-LC, 3y-RC and 3y-OS rates were 93.5%, 93.5% and 78.0%, respectively. Bilateral Level IB received unplanned high-dose irradiation with a mean dose (Dmean) ≥50 Gy in 60% of patients. The average Dmean of bilateral SMGs was approximately 53 Gy. CONCLUSION: ENI to Level IB may be unnecessary in IB-negative patients with NPC treated by IMRT. A further Phase 3 study is warranted. ADVANCES IN KNOWLEDGE: Based on the results of this first Phase 2 study, we suggest omitting ENI to Level IB in Ib-negative patients with NPC with extensive nodal disease treated by IMRT.

[Application study of the 2008 staging system of nasopharyngeal carcinoma].

BACKGROUND AND OBJECTIVE: The 2008 staging system of nasopharyngeal carcinoma (NPC) was generated based on the NPC 92 and AJCC staging system. It remains open to be consummated. This study was to evaluate its rationality as well as compare the stage distribution among the 3 staging systems, by using of MRI imaging. METHODS: MRI data was collected from a cohort of 177 cases of untreated NPC for retrospective review. We accepted the nasal involvement criteria of 2008 staging system, in which the borderline between the nasal cavity and nasopharynx was a line linked between both posterior walls of the maxillary sinus, for all of the 3 systems. RESULTS: Involvement of oropharynx, nasopharynx, soft palatine, prevertebral muscles, post-styloid space, intracranial, orbit, 1st and/or 2nd cervical body are 100% accompanied with other same or more advanced T-stage classifications. The same situations happened in more than 95% of involvement of the medial pterygoid muscle or masticator space beyond it. Cervical lymph node metastasis (LNM) accounted for 76.3%. Proportion of metastatic lymph node extracapsular extension (ECE) and/or bilateral neck LNM elevated as maximum diameter of the node increased, no matter transverse or longitudinal. There were 11 cases of parotid LNM in this group. Advanced stage accounted for 81.4%, 78.5% and 75.7% in 2008, UICC and NPC 92 staging system, respectively, without statistic difference. CONCLUSION: Nasal involvement criteria and T-stage classification of the medial pterygoid muscle defined by NPC 2008 staging system seems reasonable. Stage distribution is also similar to the other 2 systems. However, diameter of the LNM might not be a prognostic factor. Parameters such as how to classify a parotid LNM, or a node which occupies more than one region, require further clarify.