Primary allylic alcohols are isomerized to aldehydes in the presence of Pd(OH) 2 and homologated to a,b-unsaturated carbonyl derivatives in one-pot by addition of stabilized Wittig ylides in a sequential fashion. When the reaction was prolonged by addition of more catalyst, a hydrogenation step succeeds the Wittig olefination. In addition, sequential isomerization-Wittig olefination-oxaMichael addition reaction provides tetrahydropyran with high diastereoselectivity.

The total synthesis of herbarumin III (1) was achieved via an alkynide ion addition onto a chiral aldehyde and LiAlH 4 /LiI reduction as key steps (Scheme 2).Introduction. -Natural lactones with a medium ring size between eight to eleven [1] are attracting the attention of several groups because of their significant biological importance, but their syntheses are challenging. The phytotoxic lactone herbarumin III (1) was isolated by Mata and co-workers from the fermentation broth and mycelium of the fungus Phoma herbarum along with herbarumin I (2) and II (3) [2]. The structure of 1 was elucidated by spectroscopic methods combined with molecular modeling. Herbarumin III showed significant phytotoxic effects when tested against seedlings of A. hypochondriacus [3]. The herbarumin macrolides 1 -3 interact with bovine-brain calmodulin and inhibited the activation of the calmodulin-dependent enzyme camp phosphodiesterase. Considering its structure and selective biological profile, herbarumin III has attracted a great deal of interest among synthetic organic chemists. Consequently, the synthesis of 1 has been reported by various research groups [4]. Herein, we report a protocol for the synthesis of herbarumin III based on an alkynide ion addition onto a chiral aldehyde and reagent-controlled synthesis.

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A novel, efficient synthesis of a series of functionalized, benzo-annelated decahydrofuro [3,2-h] [1,6]naphthyridine derivatives 3 has been achieved. The protocol is based on the intramolecular hetero-Diels-Alder (IMHDA) reaction of in situ formed imines derived from an N-prenylated sugar aldehyde 1 and different aromatic amines 2 in the presence of bismuth(III) chloride as catalyst. The reactions could be run under very mild conditions at room temperature, and were complete within 30 min, affording exclusively and stereoselectively the corresponding trans-fused products 3 in good-to-excellent yields (Table).Introduction. -The Diels-Alder reaction with its myriad applications has enabled the construction of complex molecules and afforded numerous unparalleled solutions to a diverse range of synthetic puzzles provided by nature in the form of natural products. Over recent years, intramolecular hetero-Diels-Alder (IMHDA) reactions have found wide application in numerous reactions of prominence in organic synthesis because of their economical and stereocontrolled nature in the synthesis of polycyclic skeletons [1] [2]. These reactions allow the formation of two or more rings at once at the expense of sequential chemical transformations.We have reported [3] several BiCl 3 -catalyzed IMHDA reactions of imines derived from O-, N-, and S-prenyl derivatives of aldehydes and anilines. However, there is no single report on IMHDA reactions using N-prenylated sugar aldehydes derived from Dglucose and amines. One possible target structure of such reactions is furo[3,2-h][1,6]naphthyridine (A), a rare and basically non-investigated heterocyclic systems, in contrast to the isomeric furo [2,3-h][1,6]naphthyridine skeleton (B), which can be readily made by Smiles rearrangement followed by cyclization [4]. These [2,3-h] [1,6]naphthyridine derivatives have shown relaxation activity against tracheal muscular contraction induced by carbamylcholine chloride.In the present work, we introduce a novel, stereoselective method for the preparation of a series of complex, tetra-or pentacyclic furo[3,2-h][1,6]naphthyridine derivatives from anilines or naphthalene-1-amine and a simple sugar derivative.