Bruton's tyrosine kinase (BTK), a cytoplasmic tyrosine kinase, plays a central role in immunity and is considered an attractive target for treating autoimmune diseases. The use of currently marketed covalent BTK inhibitors is limited to oncology indications based on their suboptimal kinase selectivity. We describe the discovery and preclinical profile of LOU064 (remibrutinib, 25), a potent, highly selective covalent BTK inhibitor. LOU064 exhibits an exquisite kinase selectivity due to binding to an inactive conformation of BTK and has the potential for a best-in-class covalent BTK inhibitor for the treatment of autoimmune diseases. It demonstrates potent in vivo target occupancy with an EC 90 of 1.6 mg/kg and dose-dependent efficacy in rat collagen-induced arthritis. LOU064 is currently being tested in phase 2 clinical studies for chronic spontaneous urticaria and Sjoegren's syndrome.

Additions of lithiated alkoxyallenes to D-glyceraldehydebased nitrones 1 and 2 did not provide the expected hydroxylamine derivatives. Instead, a novel [3+3] cyclization process furnished 4-alkoxy-3,6-dihydro-2H-1,2-oxazines 9-14 with excellent syn selectivities and in moderate to good yields. Through precomplexation of the nitrones the corresponding anti-configured 1,2-oxazines 9, 10 and 13 could be obtained with high stereoselectivity. The reactions of nitrones 3-6, derived from D-erythrose or D-threose, generally proceeded less diastereoselectively, but reasonable yields of anti-configured 1,2-oxazines such as anti-17 and anti-19 could be obtained under Lewis acid promotion conditions. This was also the case for reactions of the D-arabinose-derived nitrone 7, which provided the anti-1,2-oxazines 23 and

[reaction: see text] Diastereoselective hydroborations of enantiopure 3,6-dihydro-2H-1,2-oxazines led to dihydroxy-substituted 1,2-oxazines. Samarium diiodide-induced N-O bond cleavage generated 1,4-amino alcohols which were recyclized to polyhydroxylated pyrrolidines which are potential glycosidase inhibitors.

Acid‐catalyzed transformations of carbohydrate‐derived 3,6‐dihydro‐2H‐1,2‐oxazines such as 1, 5 and 13 provided a set of enantiopure furano‐1,2‐oxazines or pyrano‐1,2‐oxazines. The reaction conditions determined the degree of solvolysis of the compounds. An X‐ray analysis of product 6 revealed an interesting network of hydrogen bonds. Reductive cleavage of the N–O bond of the 1,2‐oxazines either by hydrogen/palladium or by samarium diiodide furnished enantiopure aminofuran and ‐pyran derivatives, e.g. 9 and 11 or compound 16, which can be regarded as protected 4‐amino‐1,4‐dideoxyhex‐3‐ulose or 4‐amino‐1,4‐dideoxyoct‐3‐ulose derivatives. We thus have established a short and stereocontrolled route to amino carbohydrate derivatives with 1,2‐oxazines as crucial relay compounds. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A highly diastereoselective addition of lithiated methoxyallene 3 to chiral cyclic nitrones 1 and 2 provided N-hydroxy pyrrolidines 4 and 5, respectively, which cyclized to bicyclic 1,2-oxazines 6 and 7 by simple stirring in dilute CH 2 Cl 2 solution. Storage of 4 in a more concentrated solution led to formation of a 60:40 mixture of 1,2-oxazine 6 and amine ox-