Synthesis of 9-methyl-1H-[1,4]thiazino[3,2-g]quinoline-2,5,10(3H)-trione, the B,C,D ring core of the shermilamine alkaloids

Abstract

Synthesis of 9-methyl-1H-[1,4]thiazino[3,2-g]quinoline-2,5,10(3H)-trione (4), from N-(4-bromo-2,5-dimethoxyphenyl)acetamide (23) is described. Oxidative cyclisation of 2,2'-disulfanediylbis[N-(2,5-dimethoxyphenyl)acetamide] (19) to 5,8-dimethoxy-2H-1,4-benzothiazin-3(4H)-one (7b) is also reported.

Decomposition of benzoylthioureas into benzamides and thiobenzamides under solvent-free conditions using iodine–alumina as the catalyst and its mechanistic study by density functional theory

“…7 Several methodologies to check the reaction conditions, such as in a liquid phase, 8 in a vapor phase, 9 in supercritical water, 10 and in ionic liquids, 11 have been developed. 15 Recently, solvent-free organic synthesis using inorganic supports has become a popular method 16 and attracted immense interest as an environmentally benign methodology, because it often leads to high yields, clean reactions, and shorter reaction times. In recent years, molecular iodine (I 2 ) has emerged as a useful catalyst for various organic transformations because of its inexpensive, non-toxic, ready availability and eco-friendly nature.…”

A Convenient Preparation of 7-Bromo-2H-1,4-benzothiazine-3,5,8(4H)-trione and Its Application in the Synthesis of the Conaquinone B Skeleton

“…Recently, Townsend and Jackson failed to obtain 6 from 2,5-dimethoxyaniline. 6 Taking into account that a known method to obtain 2H-1,4-benzothiazinones is by cyclization of (2-nitrophenylsulfanyl)acetate esters, 7 we decided to apply the reaction of methyl thioglycolate with 2-nitro-1,4-benzoquinones 8 to the preparation of a suitable precursor of 4. Nitrobenzoquinones could be useful substrates for the synthesis of heterocyclic quinones, 9 but their use is limited by their low stability at room temperature.…”

Bioactive Marine Alkaloids

“…The purple colored colonial tunicate Trididemnum sp. [46][47][48] has furnished two related bases, shermilamine-A (39) 47 and shermilamine-B (40). 47 Kuanoniamines A-D (41-44), along with shermilamine-B (40), are found in the lamellarid mollusc Chelynotus semperi and its prey, an unidentified tunicate, both collected in Pohnepei.…”

“…[46][47][48] has furnished two related bases, shermilamine-A (39) 47 and shermilamine-B (40). 47 Kuanoniamines A-D (41-44), along with shermilamine-B (40), are found in the lamellarid mollusc Chelynotus semperi and its prey, an unidentified tunicate, both collected in Pohnepei. 43 Kuanoniamines-B (42) and D ( 44) are homologues of kuanoniamine C having isovaleramide and acetamide side chains, respectively.…”

“…Molecular formula of segoline A (47) was established as C 23 H 19 N 3 O 3 . Intensive 1D and 2D NMR experiments such as COSY, NOE, short-and long-range CH correlations, COLOC, and HETCOSY studies were conducted on (47). The proton NMR data revealed a trisubstituted benzo-3,6-diazaphenanthroline ring system for segoline A.…”