Total Synthesis of the Marine Alkaloid (.+‐.)‐Lepadiformine via a Radical Carboazidation.

Abstract

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Cutting-Edge and Time-Honored Strategies for Stereoselective Construction of C–N Bonds in Total Synthesis

“…629 The one-pot intramolecular amine generation/reductive amination was also employed by Renaud and co-workers in a concise 10-step synthesis of the marine alkaloid lepadiformine in 15% overall yield from cyclohexanone (Scheme 152b). 630 Under hydrogenation conditions, azide 152-3 was reduced to a primary amine, and a consecutive stereoselective reductive amination afforded bicyclic compound 152-4. Subsequent lactam formation gave 152-5 in 72% overall yield.…”

Total Synthesis of (±)-Fasicularin through Double Consecutive Epimerizations

“…Treatment with Lawesson's reagent successfully yielded the corresponding thiolactam 14c in excellent yield. However, subsequent lithium acetylide addition and LiAlH 4 reduction 13 were invariably unsuccessful (entry 1). Electrophilic activation within the Tf 2 O/DTBMP system followed by CH 2 �CHMgBr addition and LiAlH 4 reduction 14 led to significant amounts of decomposed material (entry 2), while partial reduction within the DIBAL-H/n-BuLi ate complex and subsequent TMSCN addition 15 led primarily to recovered starting material (entry 3).…”