Structurally dependent behavior of the nitromethyl group of aliphatic γ-nitrothioamides under nitrile oxide generation reaction conditions

Sośnicki, Jacek G.; Westerlich, Sławomir

doi:10.1016/s0040-4039(01)02369-3

Cited by 7 publications

(1 citation statement)

References 20 publications

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“…4,5 The latter have been found to be valuable substrates in the synthesis of chiral pyrrolidin-2-ylidene carboxylates 5 and 4-isothiocyanato-2-piperidinone derivatives. 6 Since tertiary nitroalkanes can act as radical precursors 7 and react with alkenes, 8 we started the synthesis of cyclopentane bridged piperidine derivatives A via 4-nitroalkyl-3-allylthiolactams B (Scheme 1). Thus, a nitroalkyl group should be introduced by Michael addition of nitroalkanes to a,bunsaturated thiolactams D to obtain C and the alkenyl substitutent via thio-Claisen rearrangement to get B.…”

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confidence: 99%

New Stereoselective Synthesisof 2-Allyl-4-nitroalkylpiperidine-2-thiones and their Transformationto Annulated Piperidinones

Sośnicki¹

2003

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Highly stereocontrolled access to trans-3-allyl-4nitro-alkyl-1,6-disubstituted d-thiolactams was achieved starting from piperidine-2-thione or commercially available 2-mercaptopyridine via Michael-addition of nitroalkanes to 5,6-dihydropyridin-2-thiones, S-allylation and thio-Claisen rearrangement. The corresponding lactams obtained by desulfurisation, were found to be suitable precursors for the construction of trans-fused bicyclic 2-piperidinone derivatives (octahydro[2]pyrindinones) in a regio-and stereoselective radical 5-exo-trig annulation process.The piperidine ring is a common structural motif present in naturally occurring and synthetic compounds. 1 Due to a wide range of biological activities 2 associated with the piperidine moiety, the synthesis of multifunctionalized piperidines is still an attractive synthetic goal. 3 Among the recent efforts in this area, we have succeeded in accomplishing a 1,4-addition of C-, N-and S-nucleophiles to a,b-unsaturated thiolactams affording 4-substituted thiolactam, 4-nitromethylthiolactams included. 4,5 The latter have been found to be valuable substrates in the synthesis of chiral pyrrolidin-2-ylidene carboxylates 5 and 4-isothiocyanato-2-piperidinone derivatives. 6 Since tertiary nitroalkanes can act as radical precursors 7 and react with alkenes, 8 we started the synthesis of cyclopentane bridged piperidine derivatives A via 4-nitroalkyl-3-allylthiolactams B (Scheme 1). Thus, a nitroalkyl group should be introduced by Michael addition of nitroalkanes to a,bunsaturated thiolactams D to obtain C and the alkenyl substitutent via thio-Claisen rearrangement to get B. Radical cyclization would lead to the anticipated bicyclic piperidines A. All three key steps can be expected to occur with stereoselectivity. The synthetic goal seemed to be interesting, because cyclopentane-piperidine fused moieties are found in some naturally occurring compounds e.g. magellanine, 9a kopsilactone, 9b skytanthine alkaloids. 9c,d Certain bicyclic piperidines can act as effective, cyclic constrained P 1 ¢ ligand of HIV-1 protease inhibitor (Scheme 1). 9e Until now the most common approaches to piperidine-cyclopentane fused systems were based on the initial stereoselective formation of substituted cyclopentane ring finalized by azaheterocyclization. 9a,9c-e

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confidence: 99%