A stereoselective method for the synthesis of substituted tetrahydropyran derivatives employing a tandem S(N)2-Michael addition sequence to vinylogous carbonates is developed. The method is extended to the synthesis of bicyclic ether motifs present in polyether ladder toxins.

A new, highly stereoselective intramolecular cyclopropanation of vinylogous carbamates with carbenes in the presence of Cu(acac)(2) as the catalyst has been developed for the construction of cyclopropapyrrolidinones. The 'syn' isomer of N-DAC can be converted to the 'anti' isomer by simple silica gel treatment. Regioselective cleavage of each of the cyclopropane bonds of these two acceptor substituted N-DACs led to a diverse array of azacycles.

Ir(I)-catalyzed enantioselective decarboxylative allylic etherification of aryl allyl carbonates provides aryl allyl ethers. Key to the generality and high stereoselection of the reaction is the use of the intramolecular decarboxylative allylation process and [Ir(dbcot)Cl](2) as an Ir(I) source. Ir(I)-catalyzed diastereoselective decarboxylative allylic etherification, combined with asymmetric aldehyde crotylation and cross metathesis, can furnish monoprotected 2-methyl-1,3-diols (starting from simple aldehydes) with high diastereoselectivities.

An efficient strategy is developed for the synthesis of 1,2,2-trisubstituted indane derivatives employing a tandem S N 2-Michael reaction sequence. The method is extended towards the synthesis of spiroindanes and indanopiperidines.Indane derivatives are important synthetic targets in organic synthesis as they show remarkable biological and pharmacological properties. 1 A variety of natural and unnatural products contain the indane framework as part of their structures. Substituted indane derivatives have found use as precursors in the synthesis of aesthetically pleasing structural motifs such as benzofenestranes and centropolyindanes. 2 Indane-derived chiral ligands have found applications in transition-metal-catalyzed processes. 3 As a result, the synthesis of substituted indanes continues to attract attention from synthetic chemists. 4Tandem reactions are highly desirable in present day synthesis because they enhance molecular complexity in a 'single pot' process, thereby minimizing the number of laboratory operations required and the quantities of chemicals and solvents used. 5 Herein, we report on the stereoselective synthesis of 1,2,2-trisubstituted indane derivatives employing tandem S N 2-Michael addition sequence. 6 Scheme 1We envisaged that the 1,2,2-trisubstituted indane derivatives can be assembled by reaction of an active methylene compound with an o-halomethyl cinnamate derivative employing a tandem alkylation-Michael addition sequence (Scheme 1). Here, it was anticipated that the active methylene compound will first undergo intermolecular S N 2 substitution reaction followed by intramolecular Michael addition reaction leading to the desired target. To test our hypothesis, we decided to use chloroester 1 6a and chloroketone 2 as acceptors in our study. These substrates can be readily prepared in four steps starting from commercially available phthalic anhydride (3) as depicted in Scheme 2. Thus, reduction of phthalic anhydride in refluxing THF with lithium aluminum hydride furnished diol 4. Reaction of diol 4 with concentrated HCl in toluene produced the chloroalcohol 5 in 90% yield. 7 Oxidation of the alcohol moiety in 5 with pyridinium chlorochromate (PCC) in CH 2 Cl 2 gave aldehyde 6. The Wittig olefination of aldehyde 6 with ylide 7 yielded ester 1, whereas that with ylide 8 furnished ketone 2 in good overall yields.

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