Transition metal catalyzed regioselective amination of the cage B(4)–H bond in o-carboranes has been achieved for the first time using O-benzoyl hydroxylamines or organic azides as the amination ...reagents, leading to the preparation of a series of tertiary and secondary carboranyl amines. Both amination reactions proceeded under mild conditions without the addition of any external oxidants. Hydrogenolysis of the resultant product 4-N(CH2Ph)2-o-carborane afforded the primary carboranyl amine, 4-amino-o-carborane, in quantitative yield.
Palladium‐catalyzed direct dialkenylation of cage B(4,5)H bonds in o‐carboranes has been achieved with the help of a carboxylic acid directing group, leading to the preparation of a series of ...4,5‐trans‐(ArCHCH)2‐ocarboranes in high yields with excellent regioselectivity. The traceless directing group, eliminated during the course of the reaction, is responsible for controlling regioselectivity and dialkenylation. A possible catalytic cycle is proposed, involving a tandem sequence of PdII‐initiated cage BH activation, alkene insertion, β‐H elimination, reductive elimination, and decarboxylation.
Giving directions: Pd‐catalyzed direct dialkenylation of cage B(4,5)H bonds in o‐carboranes has been achieved using a carboxylic acid directing group, leading to the preparation of a series of 4,5‐trans‐(ArCHCH)2‐o‐carboranes in high yields and with excellent regioselectivity.
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 H2 and 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-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.
Acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) are usually associated with poor outcomes, especially in high‐risk AML/MDS. Allogeneic hematopoietic stem cell transplantation ...(allo‐HSCT) is the only curative option for patients suffering from high‐risk AML/MDS. However, many patients relapse after allo‐HSCT. Novel therapy to prevent relapse is urgently needed. Both the BCL‐2 inhibitor venetoclax (VEN) and the hypomethylating agent decitabine (DEC) possess significant antitumor activity effects against AML/MDS. Administration of DEC has been shown to ameliorate graft‐versus‐host disease (GVHD) and boost the graft‐versus‐leukemia (GVL) effect post‐transplantation. We therefore conducted a prospective study (ChiCTR1900025374) to examine the tolerability and efficacy of a maintenance therapy of low‐dose decitabine (LDEC) plus VEN to prevent relapse after allo‐HSCT for high‐risk AML/MDS patients. Twenty patients with high‐risk AML (n = 17) or high‐risk MDS (n = 3) post‐transplantation were recruited. Approximately day 100 post‐transplantation, all patients received LDEC (15 mg/m2 for 3 d) followed by VEN (200 mg) on d 1‐21. The cycle interval was 2 mo, and there was 10 cycles. The primary end points of this study were rates of overall survival (OS) and event‐free survival (EFS). The secondary endpoints included adverse events (AEs), cumulative incidence of relapse (CIR), nonrelapse mortality (NRM), incidences of acute GVHD (aGVHD) and chronic GVHD (cGVHD), and incidences of viral infection after allo‐HSCT. Survival outcomes were assessed using Kaplan‐Meier analysis. The median follow‐up was 598 (149‐1072) d. Two patients relapsed, 1 died, and 1 is still alive after the second transplant. The 2‐y OS and EFS rates were 85.2% and 84.7%, respectively. The median 2‐y EFS time was 525 (149‐1072) d, and 17 patients still had EFS and were alive at the time of this writing. The most common AEs were neutropenia, anemia, thrombocytopenia, neutropenic fever, and fatigue. Grade 2 or 3 AEs were observed in 35% (7/20) and 20% (4/20) of the patients, respectively. No grade >3 AEs were observed. aGVHD (any grade) and cGVHD (limited or extensive) occurred in 55% and 20% of patients, respectively. We conclude that LDEC + VEN can be administered safely after allo‐HSCT with no evidence of an increased incidence of GVHD, and this combination decreases the relapse rate in high‐risk AML/MDS patients. This novel maintenance therapy may be a promising way to prevent relapse in high‐risk AML/MDS patients.
The results of the current study suggest that maintenance treatment with LDEC combined with VEN introduced nearly 3 mo after allo‐HSCT is efficacious, with an acceptable toxicity profile and impressive long‐term disease control.
Transition metal catalyzed, regioselective carborane‐cage B(4)−H iodination, bromination, and chlorination as well as B(4,5)−H diiodination were achieved by using NXS (X=I, Br), FeCl3, or IOAc as the ...halogenating agent, respectively. A series of previously inaccessible B(4)‐halogenated o‐carboranes were synthesized in a simple one‐pot process, and proved to be valuable synthons for the functionalization of carboranes. Mono‐ and di‐selectivity can be controlled by in situ removal of the carboxy directing group. The resultant 4‐I‐o‐C2B10H11 can serve as a versatile feedstock for the construction of cage B−C(sp2), B−C(sp), B−O, and B−N bonds.
Access granted: Transition metal catalyzed, regioselective cage B(4)−H iodination, bromination, and chlorination as well as B(4,5)−H diiodination were achieved to grant access to a series of previously inaccessible B(4)‐halogenated o‐carboranes in a simple one‐pot process (see scheme). Mono‐ and di‐selectivity can be controlled by in situ removal of the carboxyl directing group.
A one-pot strategy for efficient and facile synthesis of C,B-substituted carborane-fused N-polyheterocycles is reported. A rhodium catalyzed cascade cyclization of carboranyl N-arylimines with vinyl ...ketones enables the effective construction of three new B-C and C-C bonds in one reaction. Both carboranyl B-H and aryl C-H bonds are sequentially activated, leading to a series of previously unavailable C,B-substituted carborane-fused cyclopenta
quinoline derivatives, for potential applications in pharmaceuticals and materials, in a step-economical manner. The successful isolation and structural identification of a key intermediate provide solid evidence for the reaction mechanism, involving a tandem sequence of regioselective B-H activation, alkene insertion, nucleophilic cyclization, C-H activation, nucleophilic cyclization, dehydration and oxidative aromatization.
Summary of main observation and conclusion
Ir‐catalyzed cascade dehydrogenative CH/BH and BH/OH cross‐coupling of carboranyl carboxylic acid with readily available benzoic acid has been achieved, ...leading to the facile synthesis of previously unavailable carborano‐coumarin in a simple one‐pot process. Two cage B—H, one aryl C—H and one O—H bonds are activated to construct efficiently new B—C and B—O bonds. The cascade cyclization can stop at the first B—H/C—H cross‐coupling step by tuning the reaction conditions, resulting in a series of α‐carboranyl benzoic acid and aryl carborane derivatives. Control experiments indicate that B—H/C—H dehydrocoupling proceeds preferentially over B—H/O—H dehydrocoupling, and both directing groups and oxidants are crucial for this reaction. An iridium(V) intermediate is proposed to be involved in the catalytic cycle.
Ir‐catalyzed cascade dehydrogenative CH/BH and BH/OH cross‐coupling of carboranyl carboxylic acid with readily available benzoic acid has been achieved, leading to the facile synthesis of previously unavailable carborano‐coumarin in a simple one‐pot process, in which two B—H, one C—H and one O—H bonds are broken, while two new B—C and B—O bonds are formed.
Relapsed or refractory (R/R) acute myeloid leukemia (AML) has a poor prognosis. In this study, we evaluated chimeric antigen receptor (CAR) T cell therapy targeting CLL-1 in adults with R/R AML ...patients. Patients received conditioning chemotherapy with cyclophosphamide (500 mg/m.sup.2) and fludarabine (30 mg/m.sup.2) for 3 days and an infusion of a dose of 1-2 x 10.sup.6 CAR-T cells/kg. The incidence of dose-limiting toxicity was the primary endpoint. Ten patients were treated, and all developed cytokine release syndrome (CRS); 4 cases were low-grade, while the remaining 6 were considered high-grade CRS. No patient developed CAR-T cell-related encephalopathy syndrome (CRES). Severe pancytopenia occurred in all patients. Two patients died of severe infection due to chronic agranulocytosis. The complete response (CR)/CR with incomplete hematologic recovery (CRi) rate was 70% (n = 7/10). The median follow-up time was 173 days (15-488), and 6 patients were alive at the end of the last follow-up. CAR-T cells showed peak expansion within 2 weeks. Notably, CLL-1 is also highly expressed in normal granulocytes, so bridging hematopoietic stem cell transplantation (HSCT) may be a viable strategy to rescue long-term agranulocytosis due to off-target toxicity. In conclusion, this study is the first to demonstrate the positive efficacy and tolerable safety of CLL-1 CAR-T cell therapy in adult R/R AML. Keywords: Chimeric antigen receptor, Acute myeloid leukemia, C-type lectin-like molecule 1
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