Publications by authors named "Thiwanka B Samarakoon"

Applications of silica-ROMP reagents in a one-pot, sequential protocol have been developed for the synthesis of a variety of diverse benzoxathiazepine 1,1-dioxides. This protocol includes sulfonylation, intramolecular SNAr, alkylation with silica-supported oligomeric benzyl (Si-OBPn) and triazole (Si-OTPn) phosphates, and intermolecular SNAr addition with a number of secondary amines in one-pot to afford a variety of unique benzoxathiazepine 1,1-dioxides sultams in good to excellent yields.

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The generation of common and stereochemically rich medium-sized benzo-fused sultams via complementary pairing of heretofore-unknown (o-fluoroaryl)sulfonyl aziridine building blocks with an array of amino alcohols/amines in a modular one-pot, sequential protocol using an aziridine ring opening and intramolecular nucleophilic aromatic substitution is reported. The strategy employs a variety of amino alcohols/amines and proceeds with 6 + 4/6 + 5 and 6 + 1 cycloetherification pathways in a highly chemo- and regioselective fashion to obtain skeletally and structurally diverse, polycyclic, 10- to 11- and 7-membered benzo-fused sultams for broad-scale screening.

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A one-pot, sequential protocol is reported that involves complementary ambiphile pairing (CAP) of a vinyl sulfonamide with a variety of unprotected amino acids via aza-Michael addition and subsequent intramolecular amidation. The method generates diverse, sp(3)-rich mono- and bicyclic acyl sultams in a highly scalable manner. Modular pairing of stereochemically rich building blocks allows quick access to all possible isomers.

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The efficient synthesis of an 80-member library of unique benzoxathiazocine 1,1-dioxides by a microwave-assisted, intermolecular nucleophilic aromatic substitution (S(N)Ar) diversification pathway is reported. Eight benzofused sultam cores were generated by means of a sulfonylation/S(N)Ar/Mitsunobu reaction pairing protocol, and subsequently diversified by intermolecular S(N)Ar with ten chiral, non-racemic amine/amino alcohol building blocks. Computational analyses were employed to explore and evaluate the chemical diversity of the library.

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A combination of MACOS scale-out and ROMP-derived oligomeric triazole phosphates (OTP(n)) have been successfully utilized for the preparation of a 106-member library of triazole containing benzothiaoxazepine-1,1-dioxides. This report demonstrates the utilization of a suite of soluble OTP(n) reagents for facile (triazolyl)methylation of 10 MACOS-derived sultam scaffolds in purification-free process for parallel synthesis of small molecule collections for HTS.

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The generation of stereochemically-rich benzothiaoxazepine-1,1'-dioxides for enrichment of high-throughput screening collections is reported. Utilizing a microwave-assisted, continuous flow organic synthesis platform (MACOS), scale-out of core benzothiaoxazepine-1,1'-dioxide scaffolds has been achieved on multi-gram scale using an epoxide opening/S(N)Ar cyclization protocol. Diversification of these sultam scaffolds was attained via a microwave-assisted intermolecular S(N)Ar reaction with a variety of amines.

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The utilization of a monomer-on-monomer (MoM) intramolecular Mitsunobu cyclization reaction employing norbornenyl-tagged (Nb-tagged) reagents is reported for the synthesis of benzofused thiadiazepine-dioxides. Facile purification was achieved via ring-opening metathesis (ROM) polymerization initiated by one of three metathesis catalyst methods: (i) free metathesis catalyst, (ii) surface-initiated catalyst-armed silica, or (iii) surface-initiated catalyst-armed Co/C magnetic nanoparticles.

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The development of a microwave-assisted, intermolecular S(N)Ar protocol for the synthesis of a 126-member benzothiaoxazepine-1,1-dioxide library is reported. Diversification of 12 benzothiaoxazepine-1,1-dioxides was achieved in rapid fashion utilizing a variety of 2° amines and amino alcohols to generate an 80-member library. A second 48-member library was subsequently generated via a two-step alkylation, intermolecular S(N)Ar diversification protocol.

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A reaction pairing strategy centered on utilization of a reaction triad (sulfonylation, S(N)Ar addition and Mitsunobu alkylation) generating skeletally diverse, tricyclic and bicyclic benzofused sultams is reported. Pairing sulfonylation and S(N)Ar reactions yields bridged, tricyclic and bicyclic benzofused sultams. Application of the Mitsunobu reaction in a sulfonylation-Mitsunobu-S(N)Ar pairing allows access to benzthiazocine-1,1-dioxides, while a simple change in the order of pairing to sulfonylation-S(N)Ar-Mitsunobu affords structurally different, bridged tricyclic benzofused sultams.

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A monomer-on-monomer (MoM) Mitsunobu reaction utilizing norbornenyl-tagged (Nb-tagged) reagents is reported, whereby purification was rapidly achieved by employing ring-opening metathesis polymerization, which was initiated by any of three methods utilizing Grubbs catalyst: (i) free catalyst in solution, (ii) surface-initiated catalyst-armed silica, or (iii) surface-initiated catalyst-armed Co/C magnetic nanoparticles.

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The construction of a library of benzothiaoxazepine-1,1'-dioxides utilizing a one-pot, S(N)Ar diversification-ODCT(50) scavenging protocol is reported. This protocol combines microwave irradiation to facilitate the reaction, in conjunction with a soluble ROMP-derived scavenger (ODCT) to afford the desired products in good overall purity. Utilizing this protocol, a 78-member library was successfully synthesized and submitted for biological evaluation.

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The development of new ROMP-based oligomeric benzyl phosphates (OBP(n)) is reported for use as soluble, stable benzylating reagents. These oligomeric reagents are readily synthesized from commercially available materials and conveniently polymerized and purified in a one-pot process, affording bench-stable, pure white, free-flowing solids on multigram scale. Utilization in benzylation reactions with a variety of nucleophiles is reported.

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A formal, one-pot [4 + 4] cyclization pathway for the generation of eight-membered sultams via in situ generation of an ortho-quinone methide (o-QM) is reported. The pairing of ambiphilic synthons in a complementary fashion is examined whereby o-fluorobenzenesulfonamides are merged with in situ generated o-QM in a formal [4 + 4] cyclization pathway to afford 5,2,1-dibenzooxathiazocine-2,2-dioxide scaffolds under microwave (mW) conditions. The method reported represents the first use of an o-QM in a formal hetero [4 + 4] cyclization.

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A formal [4+3] epoxide cascade protocol utilizing ambiphilic sulfonamides and a variety of epoxides (masked ambiphiles) has been developed for the generation of benzothiaoxazepine-1,1'-dioxides and oxathiazepine-1,1'-dioxides. This protocol combines an epoxide ring-opening with either an S(N)Ar or oxa-Michael cyclization pathway.

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