Birch reductive alkylation oxidation with

We were interested in applications of the high level of stereocontrol associated with the asymmetric Birch reduction-alkylation to problems in acyclic and heterocyclic synthesis. The pivotal disconnection of the six-membered ring is accomplished by utilization of the Baeyer-Villiger oxidation (Scheme 7). Treatment of cyclohexanones 25a and 25b with MCPBA gave caprolactone amides 26a and 26b with complete regiocon-trol. Acid-catalyzed transacylation gave the butyrolactone carboxylic acid 27 from 26a and the bis-lactone 28 from 26b cyclohexanones 31a and 31b afforded the diastereomeric lactones 29 and 30. ... 

The use of 1,1-diiodomethane as an electrophile in the Birch reduction (with lithium in liquid ammonia) of electron-deficient pyrroles 915 furnished pyrrolines 916 (in high to excellent yields), which provided access to the synthetically important functionalized 5,6-dihydro-2(l//)-pyridinones 917 (via radical ring expansion), substructures commonly found in biologically active natural products (Scheme 177) <2004CC1422>. 2-(Chloroalkyl)-substituted pyrrolines 919 were duly prepared by the reductive alkylation (with l-chloro-3-iodopropane or 1-chloro -iodobu-tane) of electron-deficient pyrrole 918. Allylic oxidation then furnished lactams 920 (Scheme 178). 

A modified method for the synthesis of (139) has been described. Birch reduction of 2-acylthiophens and of 2-acyl 5-alkylthiophens, followed by alkylation with alkyl halides, gave 2-acyl-, 2-alkyl-, or 2-acyl-2,5-dialkyl-thiophens in good yields. Oxidation of these compounds to the 1,1-dioxides by MCPBA, followed by thermolysis, offers a convenient route to 1,3-dienyl ketones. The Birch reduction of 2-t-butyl-5-pivaloylthiophen to the corresponding 2,5-dihydrothiophen was a key procedure in the synthesis of... 

Birch and Slobbe have found that the intermediate anion from the reduction of 2-furoic acid can be alkylated in situ (equation 17). These dihydrofuroic acids can be oxidatively decarboxylated with LTA to afford the corresponding 2-alkylfurans in what clearly represents an attractive alternative to the standard two-step metallation-alkylation of the furan ring. 

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