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1,2-Azaborines represent a unique class of benzene isosteres that have attracted interest for developing pharmaceuticals with better potency and bioavailability. However, it remains a long-standing challenge to prepare monocyclic 1,2-azaborines, particularly multi-substituted ones, in an efficient and modular manner. Here we report a straightforward method to directly access diverse multi-substituted 1,2-azaborines from readily available cyclopropyl imines/ketones and dibromoboranes under relatively mild conditions. The reaction is scalable, shows a broad substrate scope, and tolerates a range of functional groups. The utility of this method is demonstrated in the concise syntheses of BN isosteres of a PD-1/PD-L1 inhibitor and pyrethroid insecticide, bifenthrin. Combined experimental and computational mechanistic studies suggest that the reaction pathway involves boron-mediated cyclopropane ring-opening and base-mediated elimination, followed by an unusual low-barrier 6π-electrocyclization accelerated by the BN/CC isomerism. This method is anticipated to find applications for the synthesis of BN-isostere analogues in medicinal chemistry, and the mechanistic insights gained here may guide developing other boron-mediated electrocyclizations.

We disclose herein the first example of iron-catalyzed regioselective intramolecular C–H/B–H dehydrogenative coupling, affording unprecedented C,B-substituted carborane-fused phenanthroline derivatives. The 8-aminoquinoline type auxiliaries not only serve as the bidentate directing groups but also ingeniously become the core part of the final products. The mechanistic hypothesis includes B–H activation, directing group rotation promoted by trans effect, C–H activation, and reductive elimination.

Copper-catalyzed electrochemical selective cage B–H oxygenation of o-carboranes has been achieved for the first time. Under a constant electric current (4.0 mA) at room temperature, copper-catalyzed cross-coupling of carboranyl amides with lithium phenolates results in the formation of B(4,5)-diphenolated o-carboranes via direct B–H activation, whereas the use of lithium tert-butoxide affords B(4)-monooxygenated products. This reaction does not require any additional chemical oxidants and generates H2and a lithium salt as byproducts. Control experiments indicated that a high-valent Cu(III) species is likely involved in the reaction process.

A proof-of-principle study of cascade dehydrogenative cross-coupling of carboranyl carboxylic acid with readily available benzamide has been achieved, resulting in the facile synthesis of previously inaccessible carborano-isoquinolinone derivatives in a simple one-pot process, in which two cage B–H, one aryl C–H, and one N–H bond were sequentially activated to construct efficiently new B–C and B–N bonds, respectively. Under suitable reaction conditions, such cascade cyclization can be stopped at the first B–H/C–H cross-coupling step to give a series of α-carboranyl benzamides, suggesting the preferential occurrence of B–C cross-coupling over that of B–N. The carboxylic acid directing group plays a key role in the B–C cross-coupling step, which is then removed through in situ decarboxylation. The CV results combined with control experiments indicate that high-valent Ir(V)-species may be involved in the reaction pathways, which is crucial for such cascade dehydrogenative cross-coupling reactions. The isolation and structural identification of a key intermediate, its controlled transformations, and deuterium labeling experiments support a new Ir-nitrene-mediated amination for B–H/N–H dehydrocoupling.

A proof-of-concept example of catalytic regioselective cage B(8)–H functionalization of o-carboranes has been disclosed for the first time. Under the help of an acylamino directing group at cage B(3), a series of B(8)-arylated, B(4,7,8)-triarylated and B(4,7,8)-trifluorinated o-carborane derivatives were conveniently prepared. On the basis of isolation of a key intermediate, deuterium labeling experiments and DFT calculations, a reaction mechanism involving a high-valent palladium induced “cage-walking” from B(4) to B(8) vertex is proposed to account for the regioselective B(8)–H activation.

Although haploidentical donor (HID) hematopoietic stem cell transplantation (HSCT) has achieved similar survival to HLA-identical sibling donor (ISD) transplantation, the delayed hematopoietic engraftment as well as higher incidence of graft-versus-host-disease (GVHD), results in prolonged hospitalization, higher costs, and increased morbidity. In this study, a prospective, non-randomized clinical study was designed to evaluate the outcomes of patients who underwent HID HSCT supported by cord blood or ISD HSCT. Between May 2017 and November 2020, 113 patients were enrolled to undergo HID HSCT supported by cord blood (n=88) or ISD HSCT (n=25). The cumulative incidence of neutrophil and platelet engraftment at 30days was comparable in these two groups. Importantly, there was no significant difference in the cumulative incidence of grade II-IV aGVHD at 100days (20.5% [95% confidence interval [CI]: 12.2%–28.8%] versus 12.0% [95% CI: 0.2%–23.8%], P= 0.32) and cGVHD at 1 year (19.5% [95% CI: 11.2%–27.8%] versus 16.6% [[95% CI: 1.3%–31.9%] P= 0.70) between the two groups. Among the HID and ISD groups, the 2-year disease free survival was 76.8 and 80.0% (P= 0.83), the 2-year overall survival was 82.4 and 88.0% (P= 0.66), the 2-year GVHD-free, relapse-free survival was 68.9 and 75.3% (P= 0.62), respectively. Our results indicate that HID transplantation supported by cord blood may offer a good alternative to ISD HSCT for patients with hematopoietic malignancies.Trial registration: Effect of co-infusion third party umbilical cord blood stem cells on haploidentical hematopoietic stem cell transplantation https://www.chictr.org.cnReg. No. ChiCTR-OIN-17011426.

Background:

Background:The persistence or recurrence of minimal residual disease (MRD) after chemotherapy predicts relapse of B-cell acute lymphoblastic leukemia (B-ALL). CD19-directed chimeric antigen receptor-modified T (CD19 CAR-T) cells have shown excitable response in B-ALL. Recently, some studies have shown that ALL patients with lower burden had higher CR rate and lower risk of CRS after CAR-T therapy (Park, et al, NEJM. 2018; 378(5):439-448. Lee, et al, Blood.128 (22):Abstract 218.). However, its role in chemotherapy-refractory MRD-positive B-ALL remains unclear. Here we aimed to assess the effectiveness and safety of CD19 CAR-T in MRD-positive B-ALL patients.

No relevant conflicts of interest to declare.

No relevant conflicts of interest to declare.