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Formal total syntheses of (–)-indolizidines 205A, 207A, and 235B have been accomplished using Evans aldol, Horner–Wadsworth–Emmons olefination and reductive cyclization as key reactions. [ABSTRACT FROM AUTHOR]

An intermolecular approach to the construction of 3,4-dihydro-1 H-pyrrolo[2,1- c][1,4]oxazines is reported for the first time using the oxa-Pictet-Spengler reaction. The method involves a sequence of carbon-carbon- and carbon-oxygen-bond formation between a substituted 2-(1 H-pyrrol-1-yl)ethan-1-ol and an aldehyde/ketone. p-Toluenesulfonic acid ( pTSA) was identified as a suitable catalyst to promote the reaction. The method provides a one-step conversion of various aldehydes/ketones into the corresponding 3,4-dihydro-1 H-pyrrolo[2,1- c][1,4]oxazines. [ABSTRACT FROM AUTHOR]

The first asymmetric total synthesis of the natural pyrrole lactone longanlactone has been achieved. The key reactions, a Barbier propargylation and a Paal-Knorr pyrrole synthesis, have provided easy access to the target natural product from L-aspartic acid in six steps and 31 % overall yield. The C-4 epimer of the natural product and propionyllonganlactone have also been prepared by this strategy. [ABSTRACT FROM AUTHOR]

Abstract: An enantioselective access to (−)-indolizidine alkaloids 167B, 209D, 239AB, 195B and (−)-monomorine from a new chiral synthon is described. The use of (S)-3-(Cbz-amino)-4-(tert-butyldimethylsilyloxy)butanal, obtained from l-aspartic acid, has provided efficient access of the indolizidine frame work through a Horner–Wadsworth–Emmons reaction and reductive cyclization as the key steps. [Copyright &y& Elsevier]

Key reactions in the first asymmetric total assembly of the natural pyrrole lactone longanlactone (I) are a Barbier propargylation and a Paal-Knorr pyrrole synthesis. [ABSTRACT FROM AUTHOR]