Selective preparation of αβ-unsaturated esters via the reformatsky reaction

Fung, Kwok-Keung; Schmalzl, K. J.; Mirrington, R. N.

doi:10.1016/s0040-4039(01)88873-0

Cited by 11 publications

(3 citation statements)

References 8 publications

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“…In the case of 7 a this reaction led to a separable 1:1 mixture of the desired unsaturated ester 8 a (as an unseparable E , Z ‐mixture) and the tertiary alcohol 9 a . Elimination of the latter through subsequent formation of the corresponding acetate 10 a led to a further portion of 8 a 26. In contrast to the a ‐series, reaction of 7 b and 7 c led directly to the desired unsaturated ester derivatives in a single isomeric form, that is E ‐ 11 b and Z ‐ 12 c .…”

Section: Resultsmentioning

confidence: 99%

Development of Analogues of 1α,25-Dihydroxyvitamin D3 with Biased Side Chain Orientation: Methylated Des-C,D-Homo Analogues

et al. 2001

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The discovery that 1alpha,25-dihydroxyvitamin D3 is effective in the inhibition of cellular proliferation and in the induction of cellular differentiation has led to a search for analogues in which these activities and the classical calcemic activity of this hormone are separated. In this context, the synthesis and biological evaluation are reported of the three stereoisomeric CD-ring modified structural analogues in order to enforce a particular and different orientation of the 25-hydroxylated side chain. Comparison of the results of the biological evaluation and conformational analysis of the side chain suggests one defined and "active" geometry.

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Section: Resultsmentioning

confidence: 99%

Development of Analogues of 1α,25-Dihydroxyvitamin D3 with Biased Side Chain Orientation: Methylated Des-C,D-Homo Analogues

et al. 2001

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“…As it is known that endocyclic P,y-unsaturated esters should be more stable than the exocyclic a,P-unsaturated isomers in cases such as these (19), a more specific method was sought. It was felt that the Wadsworth-Emmons phosphonate modification of the Wittig reaction (20) could provide a direct introduction of the side chain.…”

Section: Introductionmentioning

confidence: 99%

The design and synthesis of nonpeptide compounds as mimics of a conformation of methionine-enkephaline

Bélanger¹,

Dufresne²,

Scheigetz³

et al. 1982

Can. J. Chem.

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A model for the active conformation of methionine-enkephalin containing a P-turn was derived from computer modeling. Using a trans-perhydronaphthalene as a structural template and a mimic of the p-turn, target compounds were designed and synthesized. Thus, a key intermediate, trans-3-oxo-5~-formamidomethyl-8a-phenylmethylperhydronaphthalene, was prepared by two different routes from cyclohexanone.The addition of a methionine-like side-chain to this key intermediate was best achieved by a reaction with the anion of methyl 2-trimethylsilyl-4-methylthiobutanoate. This led to the preparation of an exo-tetrasubstituted double bond in high yield. Subsequent addition of tyrosine through coupling with the 5P-aminomethyl group provided the desired perhydronaphthalene mimics of met-enkaphalin.

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“…Selective reduction of the ketone was achieved with sodium borohydride (70%) and the alcohol 17 converted to its acetate 18 under standard conditions with acetic anhydride in pyridine (88%). Direct dehydration of the alcohol with phosphorus oxychloride gave a mixture of a , p and P,y unsaturated esters, a difficulty which was avoided when the diester 18 was treated with potassium tert-butoxide at room temperature for 50 min (18) to afford the triene 21 (82%). Unfortunately no conditions, thermal or Lewis acid catalysis, could be found to effect cyclization of 21 without decomposition of the sensitive spirocyclopentadiene moiety.…”

Section: Resultsmentioning

confidence: 99%

Studies of intramolecular Diels–Alder reactions: preparation of methyl spiro[2.4]hepta-4,6-dien-1-yl esters and their internal cycloaddition reactivity

Gallacher¹,

Ng²,

Attah-Poku³

et al. 1984

Can. J. Chem.

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Different routes to the spiro[2.4]hepta-4,6-dien-1-yl esters 5, 6, 7, 26, and 28 are described and their intramolecular Diels–Alder reactivity examined. A sidechain oxygen substituent is essential for cyclization although its exact role in the cycloaddition remains obscure. The trienes 5, 6, and 28 cyclize to the tetracyclo[5.4.01.7.04.6.06.10]undecenes 9, 10, and 30 which are useful synthetic intermediates for the preparation of sesquiterpenes.

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Selective preparation of αβ-unsaturated esters via the reformatsky reaction

Cited by 11 publications

References 8 publications

Development of Analogues of 1α,25-Dihydroxyvitamin D3 with Biased Side Chain Orientation: Methylated Des-C,D-Homo Analogues

Development of Analogues of 1α,25-Dihydroxyvitamin D3 with Biased Side Chain Orientation: Methylated Des-C,D-Homo Analogues

The design and synthesis of nonpeptide compounds as mimics of a conformation of methionine-enkephaline

Studies of intramolecular Diels–Alder reactions: preparation of methyl spiro[2.4]hepta-4,6-dien-1-yl esters and their internal cycloaddition reactivity

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