Diltiazem-like calcium entry blockers: a hypothesis of the receptor-binding site based on a comparative molecular field analysis model.

A series of 26 pyrrolo[2,1-c][1,4]benzothiazines, which have been already synthesized and reported to show calcium antagonist activity in both radioligand-binding assays and functional studies, were investigated using the comparative molecular field analysis (CoMFA) paradigm. Due to the lack of experimental structural data on these derivatives, the minimum energy conformers obtained by molecular mechanics calculations were used in the subsequent study. Structures were aligned following an alignment criterion based on the pharmacophoric groups of the studied compounds. The predictive ability of the CoMFA model was evaluated using a test set consisting of three representative compounds. The best 3D-quantitative structure-activity relationship model found yields significant cross-validated, conventional, and predictive r2 values equal to 0.703, 0.970, and 0.865, respectively, the average absolute error of predictions being 0.26 log unit. The predictive capability of this model was also tested on a further test set of molecules consisting of diltiazem and nine pyrrolo[2,1-d][1,5]benzothiazepines endowed with calcium antagonist activity. The accurate results obtained also in this case revealed the robustness of the model. On the basis of the same alignment, the structural moieties of the studied calcium entry blockers which are thought to contribute to the biological activity were identified, and a possible receptor-binding site for all these compounds is presented taking into account the information derived from the analysis of the steric and electrostatic CoMFA contour maps.

Novel ligands specific for mitochondrial benzodiazepine receptors: 6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives. Synthesis, structure-activity relationships, and molecular modeling studies.

A novel class of ligands specific for MBR receptors has been identified: 6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives. The majority of newly synthesized esters 37-64 as well as some intermediate ketones showed micro- or nanomolar affinity for [3H]PK 11195 binding inhibition. A SAR study on 42 compounds and a molecular modeling approach led to a preliminary structural selectivity profile: the 6,7-double bond, the carbamoyloxy, alcanoyloxy, and mesyloxy side chains at the 7-position, and the prospective chloro substitution at the 4-position seemed to be the most important structural features improving affinity. Therefore, 7-[(dimethylcarbamoyl)oxy]- and 7-acetoxy-4-chloro-6-phenylpyrrolo[2,1-d][1,5]benzothiazepine (43 and 57) were synthesized. With 7-[(dimethylcarbamoyl)oxy]-6-(p-methoxyphenyl)pyrrolo[2,1- d][1,5]benzothiazepine (65), these were the most promising compounds with IC50s of respectively 9, 8, and 9 nM, under conditions where PK 11195 had an IC50 of 2 nM.

Pyrrolo[2,1-c][1,4]benzothiazines: synthesis, structure-activity relationships, molecular modeling studies, and cardiovascular activity.

The synthesis and pharmacological evaluation of a series of pyrrolo[1,4]benzothiazine derivatives are described. These compounds, related to diltiazem, have been shown to be representative of a novel series of calcium channel antagonists. The IC50S for inhibition of [3H]nitrendipine binding calculated by radioreceptor assay on rat cortex and rat heart homogenates showed that some of the described compounds possess an affinity equal to or higher than those of the reference calcium antagonists verapamil and cis-(+)-diltiazem. Furthermore, the alteration of the benzothiazepinone system of diltiazem to the pyrrolo[1,4]benzothiazine system of the title compounds resulted in a clear-cut selectivity for cardiac over vascular tissue, as shown in functional studies. In fact comparison of calcium antagonist activity on guinea pig aorta strips with the negative inotropic activity, determined by using an isolated guinea pig left atrium, revealed that the compounds examined displayed higher selectivity than the reference standard, within a wide variation of data. A number of structure-activity relationship trends have been identified, and possible explanation is advanced in order to account for the observed differences in selectivity. Prerequisite for in vitro calcium channel-blocking activity is the presence of two pharmacophores, namely, the substitution at C-4 and the substitution on the pyrrole ring. Two of the tested compounds, 8b and 28a, were identified as potent calcium antagonists selective for cardiac over vascular tissue.

A concerted study using binding measurements, X-ray structural data, and molecular modeling on the stereochemical features responsible for the affinity of 6-arylpyrrolo[2,1-d][1,5]benzothiazepines toward mitochondrial benzodiazepine receptors.

The 7-(acyloxy)-6-arylpyrrolo[2,1-d][1,5]benzothiazepine derivatives have been recently proposed as a new class of ligands specific for the mitochondrial benzodiazepine receptor (Fiorini et al. J. Med. Chem. 1994, 37, 1427-1438) (Greco et al. J. Med. Chem. 1994, 37, 4100-4108). In this paper we report the X-ray crystallographic structures of three potent (1-3) and two inactive (4 and 5) previously described benzothiazepines, as well as binding affinity constants for two newly assayed analogs in which the acyloxy side chain was replaced by a methoxy group (6) or removed (7). Structure-affinity relationships and molecular mechanics calculations performed using crystal structures as references have led to a revised 3D pharmacophore model accounting for all the data available up until now. Interestingly, the hypothetical receptor-bound conformations of 1-3 display a considerable degree of similarity with their crystal geometries. Additional calculations have confirmed that the poor affinities of benzothiazepines bearing an aroyloxy group (4 and 5) should be ascribed to the steric and/or electronic features of the side chain aryl moieties rather than to unfavorable conformational properties.

Novel and highly potent 5-HT3 receptor agonists based on a pyrroloquinoxaline structure.

The synthesis and the biological evaluation of a series of novel pyrroloquinoxaline derivatives are described. In binding studies several compounds proved to be potent and selective 5-HT3 receptor ligands. The most active pyrroloquinoxalines, 11d and 11e, showed a subnanomolar affinity for 5-HT3 receptor and were able to functionally discriminate the central and peripheral 5-HT3 receptor, being agonists and antagonists, respectively. In functional studies ([14C]-guanidinium accumulation test in NG 108-15 cells, in vitro) most of the synthesized compounds showed clear-cut 5-HT3 agonist properties. In in vivo studies on the von Bezold-Jarisch reflex test (a peripheral interaction model) the behavior of the tested compounds ranged from agonist to antagonist, while clear agonist properties were obtained with 12a on cortical acetylcholine release in freely moving rats. Pharmacokinetic studies with 11e and 12c indicate that the compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio of 17.5 and 37.5, respectively. Thus compounds 11e and 12c represent the most potent central 5-HT3 agonists identified to date that are able to cross the blood-brain barrier.

A comparative molecular field analysis model for 6-arylpyrrolo[2,1-d] [1,5]benzothiazepines binding selectively to the mitochondrial benzodiazepine receptor.

A series of 42 6-arylpyrrolo[2,1-d][1,5]benzothiazepines, which we have recently described as selective ligands of the mitochondrial benzodiazepine receptor (MBR) (Fiorini I.; et al. J. Med. Chem. 1994, 37, 1427-1438), have been investigated using the comparative molecular field analysis (CoMFA) approach. The resulting 3D-QSAR model rationalizes the steric and electronic factors which modulate affinity to the MBR with a cross-validation standard error of 0.648 pIC50 unit. A set of seven novel pyrrolobenzothiazepine congeners has successively been synthesized and tested. The CoMFA model forecasts the binding affinity values of these new compounds with a prediction standard error of 0.536.

Pyrrolobenzothiazepinones and pyrrolobenzoxazepinones: novel and specific non-nucleoside HIV-1 reverse transcriptase inhibitors with antiviral activity.

Two novel classes of pyrrolobenzothiazepinones and pyrrolobenzoxazepinones were investigated as potential anti-AIDS drugs. These compounds were found to inhibit HIV-1 reverse transcriptase (RT) enzyme in vitro and to prevent HIV-1 cytopathogenicity in T4 lymphocytes, without appreciable activity on HIV-2 cytopathic effects, and against HBV as well as calfthymus DNA alpha-polymerase. Their potency is influenced by substituents at position 6 and on the fused aromatic ring. Specifically, small lipophilic substituents at C-6 were preferred, whereas substitutions on the benzo-fused ring were found to be detrimental to activity, with respect to the unsubstituted compounds. Modification of the pie-system at C-6 is well tolerated, although the replacement of the benzo-fused with a [2,3]naphtho-fused ring leads to a less active compound. Maximum potency and specificity is achieved with a phenyl and an ethyl group at position 6 of the pyrrolobenzoxazepinone system. In the enzymatic assay the oxazepinone derivative (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5] benzoxazepin-7(6H)-one 16e (IC50 = 0.25 microM) was found to be more potent than nevirapine (IC50 = 0.5 microM), tested in the same experimental conditions using rC.dG as a template-primer. In cell culture assay benzoxazepine 16e was active against HIV-1, both wild type and AZT-sensitive, and HIV-1 (IIIB) strains, but not against HIV-2. In enzyme assay although 16e inhibited HIV-1 RT, it was inactive against the nevirapine-resistant recombinant RT Y181C at 50 microM. Molecular modeling studies suggest that these derivatives present a 3D pharmacophoric arrangement similar to that of other non-nucleoside inhibitors such as nevirapine.

New antipsychotic agents with serotonin and dopamine antagonist properties based on a pyrrolo[2,1-b][1,3]benzothiazepine structure.

The development of a synthetic approach to the novel pyrrolo[2, 1-b][1,3]benzothiazepine and its derivatives and their biological evaluation as potential antipsychotic drugs are described. In binding studies these compounds proved to be potent 5-HT2, D2, and D3 receptor ligands. The more potent benzothiazepine (+/-)-3b was resolved into its enantiomers by using HPLC techniques. In vitro testing confirmed that (-)-3b is a more potent D2 receptor ligand, maintaining high affinity for 5-HT2 receptors. In contrast, the (+)-3b enantiomer presents a 35 times higher affinity for 5-HT2 than for dopamine D2 receptors with a similar dopamine D1 receptor affinity to that of (-)-3b. Overall, (+)-3b shows an "atypical" neuroleptic binding profile, while (-)-3b has a more "classical" profile. Furthermore pharmacological and biochemical testing displayed that the novel benzothiazepine (+/-)-3b is able to increase the extracellular levels of dopamine in the rat striatum and causes a dose-related suppression of apomorphine-induced locomotor activity. At low doses (+/-)-3b does not induce catalepsy, showing atypical antipsychotic properties similar to those of olanzapine. These heterocyclic compouds represent new leads for the development of novel antipsychotic drugs with atypical properties.

Thiazolothiazepine inhibitors of HIV-1 integrase.

A series of thiazolothiazepines were prepared and tested against purified human immunodeficiency virus type-1 integrase (HIV-1 IN) and viral replication. Structure-activity studies reveal that the compounds possessing the pentatomic moiety SC(O)CNC(O) with two carbonyl groups are in general more potent against purified IN than those containing only one carbonyl group. Substitution with electron-donating or -withdrawing groups did not enhance nor abolish potency against purified IN. By contrast, compounds with a naphthalene ring system showed enhanced potency, suggesting that a hydrophobic pocket in the IN active site might accommodate an aromatic system rather than a halogen. The position of sulfur in the thiazole ring appears important for potency against IN, as its replacement with an oxygen or carbon abolished activity. Further extension of the thiazole ring diminished potency. Compounds 1, 19, and 20 showed antiviral activity and inhibited IN within similar concentrations. These compounds inhibited IN when Mn(2+) or Mg(2+) was used as cofactor. None of these compounds showed detectable activities against HIV-1 reverse transcriptase, protease, virus attachment, or nucleocapsid protein zinc fingers. Therefore, thiazolothiazepines are potentially important lead compounds for development as inhibitors of IN and HIV replication.

Pyrroloquinoxaline derivatives as high-affinity and selective 5-HT(3) receptor agonists: synthesis, further structure-activity relationships, and biological studies.

The synthesis, pharmacological evaluation, and structure-activity relationships (SARs) of a series of novel pyrroloquinoxalines and heteroaromatic-related derivatives are described. The new pyrroloquinoxaline-related ligands were tested in rat cortex, a tissue expressing high density of 5-HT(3) receptors, and on NG108-15 cells and exhibited IC(50) values in the low nanomolar or subnanomolar range, as measured by the inhibition of [(3)H]zacopride binding. The SAR studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1, L2, and L3 in the 5-HT(3) receptor cleft, while the 7-OH pyrroloquinoxaline analogue was designed to investigate hydrogen bonding with a putative receptor site H1 possibly interacting with the serotonin hydroxy group. The most active pyrroloquinoxaline derivatives showed subnanomolar affinity for the 5-HT(3) receptor. In functional studies ([(14)C]guanidinium accumulation test in NG108-15 hybrid cells, in vitro) most of the tested compounds showed clear-cut 5-HT(3) agonist properties, while some others were found to be partial agonists. Several heteroaromatic systems, bearing N-substituted piperazine moieties, have been explored with respect to 5-HT(3) affinity, and novel structural leads for the development of potent and selective central 5-HT(3) receptor agonists have been identified. Preliminary pharmacokinetic studies indicate that these compounds easily cross the blood-brain barrier (BBB) after systemic administration with a brain/plasma ratio between 2 and 20, unless they bear a highly hydrophilic group on the piperazine ring. None of the tested compounds showed in vivo anxiolytic-like activity, but potential analgesic-like properties have been possibly disclosed for this new class of 5-HT(3) receptor agonists.

Characterization of the 1H-cyclopentapyrimidine-2,4(1H,3H)-dione derivative (S)-CPW399 as a novel, potent, and subtype-selective AMPA receptor full agonist with partial desensitization properties.

(S)-CPW399 (2b) is a novel, potent, and subtype-selective AMPA receptor full agonist that, unlike (S)-willardiine and related compounds, in mouse cerebellar granule cells, stimulated an increase in [Ca(2+)](i), and induced neuronal cell death in a time- and concentration-dependent manner. Compound 2b appears to be a weakly desensitizing, full agonist at AMPA receptors and therefore represents a new pharmacological tool to investigate the role of AMPA receptors in excitotoxicity and their molecular mechanisms of desensitization.

Cardiovascular characterization of pyrrolo[2,1-d][1,5]benzothiazepine derivatives binding selectively to the peripheral-type benzodiazepine receptor (PBR): from dual PBR affinity and calcium antagonist activity to novel and selective calcium entry blockers.

The synthesis and cardiovascular characterization of a series of novel pyrrolo[2,1-d][1,5]-benzothiazepine derivatives (54-68) are described. Selective peripheral-type benzodiazepine receptor (PBR) ligands, such as PK 11195 and Ro 5-4864, have recently been found to possess low but significant inhibitory activity of L-type calcium channels, and this property is implicated in the cardiovascular effects observed with these compounds. In functional studies both PK 11195 (1-(2-chlorophenyl)-N-methyl-N-(1-methylpropyl)-3-isoquinolinecarboxa mide) and Ro 5-4864 (4'-chlorodiazepam) did not display selectivity between cardiac and vascular tissue. Therefore, several 7-(acyloxy)-6-arylpyrrolo[2,1-d][1,5]benzothiazepines, potent and selective peripheral-type benzodiazepine receptor ligands recently developed by us (3, 7-20), were subjected to calcium channel receptor binding assay. Some of these compounds showed an unexpected potency in displacing the binding of [3H]nitrendipine from L-type calcium channels, much higher than that reported for PK 11195 and Ro 5-4864 and equal to or higher than that of reference calcium antagonists such as verapamil and (+)-cis-diltiazem. Specifically, in rat cortex homogenate, our prototypic PBR ligand 7-acetoxy-6-(p-methoxyphenyl)pyrrolo[2,1-d][1,5]benzothiazepine (3) showed an IC50 equal to 0.13 nM for inhibition of [3H]nitrendipine binding. Furthermore, in functional studies this compound displayed a clear-cut selectivity for cardiac over vascular tissue. Comparison of calcium antagonist activity on guinea pig aorta strips with the negative inotropic activity, determined by using isolated guinea pig left atria, revealed that 3 displayed higher selectivity than the reference (+)-cis-diltiazem. Thus, the pyrrolobenzothiazepine 3 might represent a new tool for characterizing the relationship between the PBR and cardiac function. Furthermore, we have also investigated the structural dependence of binding to PBR and L-type calcium channels, and this study allowed us to identify a new class of potent calcium channel blockers selective for cardiac over vascular tissue, with no affinity for PBR. A number of structure-activity relationship trends have been identified, and a possible explanation is advanced in order to account for the observed differences in selectivity. Three structural features, namely, (i) the saturation of the C(6)-C(7) double bond, with a consequent higher molecular flexibility, (ii) the presence of a substituent in the benzofused ring, and (iii) a basic side chain at C-10 of the pyrrolobenzothiazepine ring system, were found to be responsible for potent L-type calcium channel antagonism and clear-cut selectivity for cardiac over vascular tissue. Among the synthesized compounds the pyrrolobenzothiazepine 62 was found to be the most promising selective calcium channel blocker. Additionally, the molecular structure determination of the key intermediate 48 by X-ray diffraction, molecular modeling, and NMR analysis is reported.

Synthesis, biological activity, and SARs of pyrrolobenzoxazepine derivatives, a new class of specific "peripheral-type" benzodiazepine receptor ligands.

The "peripheral-type" benzodiazepine receptor (PBR) has been reported to play a role in many biological processes. We have synthesized and tested a novel series of PBR ligands based on a pyrrolobenzoxazepine skeleton, in order to provide new receptor ligands. Several of these new compounds proved to be high affinity and selective ligands for PBR, and benzoxazepines 17f and 17j were found to be the most potent ligands for this receptor to have been identified to date. The SAR and the molecular modeling studies detailed herein delineated a number of structural features required for improving affinity. Some of the ligands were employed as "molecular yardsticks" to probe the spatial dimensions of the lipophilic pockets L1 and L3 in the PBR cleft and to determine the effect of occupation of L1 and L3 with respect to affinity, while other C-7 modified analogues provided information specifically on the hydrogen bonding with a putative receptor site H1. The new pyrrolobenzoxazepines were tested in rat cortex, a tissue expressing high density of mitochondrial PBR, and exhibited IC50 and Ki values in the low nanomolar or subnanomolar range, as measured by the displacement of [3H]PK 11195 binding. A subset of the highest affinity ligands was also found to have high affinities for [3H]PK 11195 and [3H]Ro 5-4864 binding in rat adrenal mitochondria. All the ligands in this subset are stimulators of steroidogenesis having similar potency and extent of stimulation as PK 11195 and Ro 5-4864 of steroidogenesis in the mouse Y-1 adrenocortical cell line.

Quinoxalinylethylpyridylthioureas (QXPTs) as potent non-nucleoside HIV-1 reverse transcriptase (RT) inhibitors. Further SAR studies and identification of a novel orally bioavailable hydrazine-based antiviral agent.

Quinoxalinylethylpyridylthioureas (QXPTs) represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTIs) whose prototype is 6-FQXPT (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis of novel heteroarylethylpyridylthioureas which were tested as anti-HIV agents. Several compounds proved to be potent broad-spectrum enzyme inhibitors and significantly inhibited HIV-1 replication in vitro. Their potency depends on the substituents and the nature of the heterocyclic skeleton linked to the ethyl spacer, and structure-activity relationships are discussed in terms of the possible interaction with the RT binding site. Although the new QXPTs analogues show potent antiviral activity, none of the compounds tested overcome the pharmacokinetic disadvantages inherent to ethylpyridylthioureidic antiviral agents, which in general have very low oral bioavailability. Through an integrated effort involving synthesis, docking studies, and biological and pharmacokinetic evaluation, we investigated the structural dependence of the poor bioavailability and rapid clearance within the thioureidic series of antivirals. Replacing the ethylthioureidic moiety with a hydrazine linker led to a new antiviral lead, offering promising pharmacological and pharmacokinetic properties in terms of antiviral activity and oral bioavailability.

Pyrrolobenzoxazepinone derivatives as non-nucleoside HIV-1 RT inhibitors: further structure-activity relationship studies and identification of more potent broad-spectrum HIV-1 RT inhibitors with antiviral activity.

Pyrrolobenzoxazepinone (PBO) derivatives represent a new class of human immunodeficiency virus type 1 (HIV-1) non-nucleoside reverse transcriptase (RT) inhibitors (NNRTs) whose prototype is (+/-)-6-ethyl-6-phenylpyrrolo[2,1-d][1,5]benzoxazepin-7(6H)- one (6). Docking studies based on the three-dimensional structure of RT prompted the synthesis and biological evaluation of novel derivatives and analogues of 6 featuring a meta-substituted phenyl or a 2-thienyl ring at C-6 and a pyridine system in place of the fused-benzene ring to yield pyrrolopyridooxazepinones (PPOs). Compared with the lead 6 and nevirapine, several of the synthesized compounds (PBOs 13a-d and PPOs 13i-k) displayed higher inhibitory activity against wild-type RT and clinically relevant mutant RTs containing the single amino acid substitutions L100I, K103N, V106A, Y181I, and Y188L. The most potent inhibitors were further evaluated for in vitro antiviral activity on lymphocytes and monocyte-macrophages, for cytotoxicity on a panel of cell lines, and for potential synergistic antiviral activity with AZT. Pharmacokinetic studies performed on 13b, 13c, and 13i showed that these compounds achieve high concentrations in the brain. The results of the biological and pharmacokinetic experiments suggest a potential clinical utility of analogues such as 13b-d, 13i, and 13j, in combination with nucleoside RT inhibitors, against strains of HIV-1 bearing those mutations that confer resistance to known NNRTI.

Antiproliferative action of pyrrolobenzoxazepine derivatives in cultured cells: absence of correlation with binding to the peripheral-type benzodiazepine binding site.

Three novel peripheral-type benzodiazepine binding site (PBBS) ligands, NF 182, 213 and 262, along with the classically used PBBS ligands, PK 11195 and Ro5-4864, were found to inhibit, at micromolar concentrations and in dose-dependent manner, the proliferation of rat C6 glioma and human 1321N1 astrocytoma, without being cytotoxic. This antiproliferative effect is mediated by arrest in the G1 phase of the cell cycle and does not appear to be mediated by a specific interaction of these ligands with the peripheral-type benzodiazepine binding site.

Non-nucleoside HIV-1 reverse transcriptase inhibitors: synthesis and biological evaluation of novel quinoxalinylethylpyridylthioureas as potent antiviral agents.

New heterocyclic derivatives of ethylpyridylthiourea, quinoxalinylethylpyridylthiourea (QXPT) and analogues, inhibited human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) activity and prevented HIV-1 cytopathogenicity in T4 lymphocytes. Several of these novel non-nucleoside RT inhibitors, with a substituted pyrroloquinoxalinone heteroaromatic skeleton, showed inhibitory activity against wild-type RT as well as against mutant RTs containing the single amino acid substitutions L1001, K103N, V106A, Y1811 and Y188L that was much greater than other non-nucleoside inhibitors such as nevirapine. Maximum potency in enzymatic assays was achieved with a fluoropyrroloquinoxaline skeleton linked to the ethylpyridylthiourea moiety (FQXPT). In cell-based assays on different cell lines and on human monocyte-macrophages, 6-FQXPT exhibited EC50 values in the nanomolar range, with a promising selectivity index. Moreover, 6-FQXPT showed synergistic antiviral activity with zidovudine.

Research on compounds with psychotropic activity. IX--Synthesis of 6-p-methoxyphenylpyrrolo[2,1-d][1,5]benzothiazepines and evaluation of their affinities for BDZ and GABA receptor subtypes.

6-p-Methoxyphenylpyrrolo[2,1-d][1,5]benzothiazepin-7(6H)-one (IV), cis-7-acetoxy-6,7-dihydro-6-p-methoxyphenylpyrrolo[2,1-d] [1,5]benzothiazepine (V) and some significant 7-acyloxy-6-p-methoxyphenylpyrrolo[2,1-d][1,5]benzothiazepines (VI a-g) were synthesized and tested in vitro for inhibition of the specific binding of 3H-Flunitrazepam, 3H-PK 11195, 3H-Muscimol and 3H-(-)Baclofen to central and peripheral benzodiazepine, GABA-A and GABA-B receptors, respectively. The compounds (IV), VI a) and (VI c) were active on the peripheral benzodiazepine receptor; in particular (VI a) and (VI c) were very active. The compound (VI g) showed an affinity, even though scanty, for the central benzodiazepine receptor.

Benzothiazine and benzothiazepine derivatives: synthesis and preliminary biological evaluation.

Several tricyclic benzothiazines and benzothiazepines have been synthesized by different intramolecular cyclization reactions. Their functionalization led to biologically active compounds. Some stereochemical aspects as well as biological responses have been outlined.