R. Mijngheer

Intramolecular diels-alder reaction with furan diene. A new synthesis of 11-keto steroids

Abstract A novel D → BCD → ABCD route to 11-keto steroids is reported involving a high yield stereoselective intramolecular Diels-Alder reaction of furan-diene 5a in water as a key-step. The dienophilic side chain is readily introduced starting from 2 via a sequence involving alkylation with ethyl 4-iodo-3-ethoxycrotonate, reduction and acid hydrolysis. The reduced adduct 8a , obtained in 24 % overall yield from 2-methyl-1,3-cyclocpentanedione, is converted into (±)-adrenosterone ( 16 via base-opening to 9 and further transformation to 13 , the dienediolate equivalent of which is a known intermediate in corticosteroid synthesis.

Intramolecular diels-alder reaction with furan-diene: Total synthesis of (±)-11-ketotestosterone and (±)-adrenosterone

Abstract A novel D → BCD → ABCD route to 11 -keto steroids is reported involving a high yield stereoselective intramolecular Diels-Alder reaction of furan-diene 12 in water as a key-step. The dienophilic side chain is readily introduced starting from 8 via a sequence involving alkylation with ethyl ( E )-3-ethoxy-4-iodo-2-butenoate, reduction and acid hydrolysis. The reduced adduct 14 is further converted into (±)-adrenosterone ( 6 ) via 24 , the dienediolate equivalent of which is a known intermediate in corticosteroid synthesis.

Intramolecular diels-alder reaction with furan-diene. A novel potential entry to steroids.☆

Abstract Depending on the reaction conditions the intramolecular Diels-Alder reaction of furan-diene 14 yields predominantly either one of two adducts 16a and 16b , which possess the necessary functionality for eventual transformation into corticosteroids. The dienophile was introduced via alkylation of the enolate, formally obtained upon lithium-liq. ammonia reduction of 3-furyl-2-methyl-2-cyclopentenone ( 7 ).

Sesquiterpene lactones : A total synthesis of (±)-vernolepin

Abstract A novel synthesis of (± )-Vernolepin ( 1 ) is described. A suitably substituted cis -fused 2-oxa-3-decalone precursor ( 29 ) has been constructed starting from 2,5-cyclohexadiene carboxylic acid via an intramolecular cyclopropanation reaction ( 23 to 18 ). The route culminated in the synthesis of Griecos lactone ( 53 ) which has previously been converted to (± )-vernolepin ( 1 ) and (± )-vernomenin ( 2 ).

Synthesis of 3-carbomethoxy-3,4-dialkylcyclohexanones

Abstract The uncatalyzed 1,4-addition of phenylmagnesium bromide and furylmagnesium iodide to methyl 5-methoxy-1,5-cyclohexadienylcarboxylate ( 1 ), directly followed by alkylation and hydrolysis leads to the corresponding cyclohexanones of type 2 (R1 and R2 trans) in moderate to high yield.