244033-95-2Relevant academic research and scientific papers
Methods for the synthesis of complex reduced isoindole, isooxyindole and isooxyquinoline libraries
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Page column 12, (2008/06/13)
Disclosed are methods of synthesizing libraries of diverse complex hexahydroisoindole, hexahydroisooxyindole and octahydroisooxyquinoline compounds through the use of a facile intramolecular Diels Alder reaction. The invention is further directed to metho
Diels-Alder Reactions of Amino Acid-Derived Trienes
Murray, William V.,Sun, Sengen,Turchi, Ignatius J.,Brown, Frank K.,Gauthier, A. Diane
, p. 5930 - 5940 (2007/10/03)
Triene precursors (1a-e, 2a-k) were constructed for substrate-controlled asymmetric Diels-Alder reactions. Boc-L-phenylalanal and Boc-L-valinal were condensed with triethyl phosphonoacetate or 2-phosphonopropionate to generate the α,β-unsaturated esters as dienophiles. Removal of the Boc group to give free amines 4a-d, which after, or without N-benzylation, were treated with 3,5-hexadienoyl chloride to give 1a-e, or with 2,4-hexadienoyl chloride to afford 2a-f. The trienes 2g-i were prepared via reductive alkylation of amines 4a-i with 2,4-hexadienal. The secondary amide triene 1a failed to yield any Diels-Alder product when heated at 170°C. The tertiary amide trienes 1b-e produced in refluxing toluene the major cycloaddition products that were cis-fused and derived from the exo transition states. Trienes 2a-k underwent surprisingly facile Diels-Alder reactions to produce the major trans-fused isomers that were derived from the endo transition states. For trienes 2b-h and 2j,k, Diels-Alder reactions proceeded at room temperature. For the primary amide 2a, the Diels-Alder reaction proceeded smoothly in refluxing toluene. The tertiary amide triene 22 was constructed to have two electron-withdrawing ester substituents at the termini of the triene. The Diels-Alder reaction of 22 took place spontaneously at room temperature upon benzoylation of the secondary amine 21 and produced a single isomer derived from the endo transition state. 1,3-Allylic strain is discussed as an important factor in control of the diastereo-selectivity.
