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The dearomative functionalization of aromatic compounds represents a fascinating but challenging transformation, as it typically needs to overcome a great kinetic barrier. Here, a catalyst-free dearomative rearrangement of o-nitrophenyl alkyne is successfully established by leveraging the remote oxygen transposition and a weak N-O bond acceleration. This reaction features high atom-, step- and redox-economy, which provides a divergent entry to a series of biologically important benzazepines and bridged polycycloalkanones. The reaction is proposed to proceed through a tandem oxygen transfer cyclization/(3 + 2) cycloaddition/(homo-)hetero-Claisen rearrangement reaction. The resulting polycyclic system is richly decorated with transformable functionalities, such as carbonyl, imine and diene, which enables diversity-oriented synthesis of alkaloid-like polycyclic framework.

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OBJECTIVE: To assess the practical and health economical values of non-invasive prenatal test (NIPT) in Changsha Municipal Public Welfare Program. METHODS: A retrospective analysis was carried out on 149 165 women undergoing NIPT test from April 9, 2018 to December 31, 2019. For pregnant women with high risks, invasive prenatal diagnosis and follow-up of pregnancy outcome were conducted. The cost-benefit of NIPT for Down syndrome was analyzed. RESULTS: NIPT was carried out for 149 165 pregnant women and succeeded in 148 749 cases (99.72%), for which outcome were available in 148 538 (99.86%). 90% of pregnant women from the region accepted the screening with NIPT. 415 (0.27%) were diagnosed as high risk. Among these, 381 (91.81%) accepted amniocentesis, which led to the diagnosis of 212 cases of trisomy 21 (PPV=85.14%), 41 cases with trisomy 18 (PPV=48.81%) and 10 cases with trisomy 13 (PPV=20.83%). The sensitivity and specificity of NIPT for trisomy 21, trisomy 18 and trisomy 13 were (97.70%, 99.98%), (97.62%, 9.97%) and (100%, 99.97%), respectively. In addition, 213 and 30 cases were diagnosed with sex chromosomal aneuploidies (PPV=46.2%) and other autosomal anomalies (PPV=16.57%), respectively. For Down syndrome screening, the cost and benefit of the project was 120.79 million yuan and 1,056.95 million yuan, respectively. The cost-benefit ratio was 1: 8.75, and safety index was 0.0035. CONCLUSION: NIPT is a highly accurate screening test for trisomy 21, which was followed by trisomy 18 and sex chromosomal aneuploidies, while it was less accurate for other autosomal aneuploidies. The application of NIPT screening has a high health economical value.

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A series of highly strained bicyclo[3.n.1]alkenones have been successfully constructed in good-to-excellent enantioselectivities and moderate-to-good yields via copper-catalyzed formal [3+3] cycloaddition. The versatile chiral cycloadducts could be selectively converted into various valuable bridge systems, which hold considerable potential for the construction of natural and bioactive compounds containing a [3.n.1] moiety.

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An unprecedented Lewis acid-catalyzed cascade 1,3-rearrangement/Friedel-Crafts cyclization of propargyl acetates is developed for the construction of polycyclic bridged indene derivatives in moderate to good yields. This practical procedure features mild conditions, broad substrate scope, and easy operation.

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A gold (I)-catalyzed reaction of enyne-ethers to rapidly construct oxa-bridged compounds via a tandem 1,2-acyloxy migration/intramolecular oxonium formation/1,2-rearrangement process was reported. The reaction was shown to be robust with a wide range of substitution patterns tolerated to provide the corresponding oxygen-containing bridged products in good to excellent yields.

RESUMEN

A catalytic [1,3] O-to-C rearrangement from enyne-ethers was developed for the rapid synthesis of diverse bridged bicyclic systems. In this reaction, a vinyl oxonium intermediate, generated in situ from enyne-ether, was the precursor for the [1,3] O-to-C rearrangement. This versatile protocol represents the first example of catalytic [1,3] O-to-C rearrangement based on ring-expansion strategy, enabling efficient access to bridged bicyclic scaffolds.