The synthesis of 9-substituted N-benzyl-8-azabicyclo[4.3.0]non-4-en-7-ones by the intramolecular Diels–Alder reaction

Brettle, R.; JAFRI, I. A.

doi:10.1039/p19830000387

Cited by 13 publications

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“…2 The reduction of the isomer (6) by magnesium and methanol thus leads to a predominance of the two racemates (1) and (2) with a cis-ring fusion. 2 The reduction of the isomer (6) by magnesium and methanol thus leads to a predominance of the two racemates (1) and (2) with a cis-ring fusion.…”

Section: Azabicyclo[430] Nonan-7-one (7) Gave (1 Rs6sr9rs) -Ns-dmentioning

confidence: 99%

The reduction of tertiary N-styrylenamides

Ainscow¹,

Brettle²,

Shibib³

1985

J. Chem. Soc., Perkin Trans. 1

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Magnesium and methanol reductian of N,9-dibenzyl-8-azabicyclo[4.3.0] non-1(6) -en-7-one (6) gave all four racemates of N,9-dibenzyl-8-azabicyclo[4.3.0]nonan-7-one (1)-(4), with a 1 3 : 6 ratio of cisfused to trans-f used products. Selective reduction of N,9d i benzyl -8-aza bicyclo [ 4.3.01 non -1 (6) ,3dien-7-one (5) gave almost exclusively the two cis-fused racemates of N,9-dibenzyl-8-azabicyclo-[4.3.0]non-3-en-7-one (9) and (10). Magnesium and methanol did not reduce (€)-N-benzyl-9benzyl idene-cis-bicyclo [4.3.0] nona n -7 -one (7) and (€) -Nbenzyl -N-( 1 -methyl -2p henylvin yl) acetamide (1 6a), but did reduce (€)-N-benzyl-N-styrylacetamide (1 6b) and (€)-and (2) -N-styrylpyrrolidin-2-one (1 3) and (14); incomplete reduction of (Z) -N-benryl-N-(1 -methyl-2-phenylvinyI)acetamide (1 5a) and (Z) -N-benzyl-N-styrylacetamide (1 5b) was observed. Reduction does not occur when the styryl phenyl group is twisted out of conjugation. Sodium and liquid ammonia reduction of (€) -Nbenzyl-9benzylidene-cis-8-azabicyclo-[4.3.0] nonan-7-one (7) gave (1 RS,6SR,9RS) -9-benzyl-8-azabicyclo[4.3.0] nonan-7-one and Nbenzyl-2-(2-phenylethyl)cyclohexane-1 -carboxamide (20). A similar cleavage of the p-styryl-nitrogen bond was observed in the reduction of (Z) -N-benzyl-N-(1 -methyl-2-phenylvinyI)acetamide (1 5a), but not with (€) -N-styrylpyrrolidin-2-one (1 3).Several tertiary N-styrylenamides were not reduced by sodium cyanoborohydride in acetic acid but Nbenzyl-9-benzylidene-cis-8-aza bicyclo [4.3.0] non-3-en -7 -one (8) and N-benzyl-9-benzylidene cjs-8-

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