Two syntheses of the C(7)–C(16)-fragment 41 of epothilone D 2 were developed that were based on tin(IV) bromide mediated reactions of 5,6-difunctionalised hex-2-enylstannanes with aldehydes. In the first synthesis, (5S)-6-tert-butyldimethylsilyloxy-5-hydroxy-2-methylhex-2-enyl(tributyl)stannane 20 was reacted with (E)-but-2-enal to give (2S,7R,4Z,8E)-1-tert-butyldimethylsilyloxy-5-methyldeca-4,...

The first total syntheses of schilancidilactones A and B, schilancitrilactone A, and 20-epi-schilancitrilactone A have been accomplished using a nickel-catalyzed cross coupling of alkyl bromide with vinyl stannane as the final step. The other key steps include late-stage C(sp)–H bromination, the oxidative cleavage of a diol to provide the requisite ketone and ester for schilancidilactones A and...

Z. Naturforsch. 53 b, 573-580 (1998); received March 30, 1998 Silicon, Germanium, Tin, Sulfur Diimides, Heterocycles, NMR Data Two tetrakis(sulfurdiimido)silanes [Si(NSNR)4 (R = rBu la, SiMe3 lb)], two germanes [Ge(NSNR)4 (R = rBu 2a, SiMe3 2b)] and one stannane [Sn(NSN?Bu)4Sn 3a] were prepared and characterised by 'H, l3C, i5N, 29Si and ll9Sn NMR spectroscopy in solution, and 3a was also studi...

A catalyst system for the Stille cross-coupling reactions of aryl mesylates and tosylates is reported. Using the combination of Pd(OAc)2, XPhos, and CsF in t-BuOH an array of aryl and heteroaryl sulfonates were successfully employed in these reactions. Morever, heteroarylstannanes, such as furyl, thiophenyl, and N-methylpyrrole, which are often prone to decomposition, were efficiently coupled u...

The first total syntheses of schilancidilactones A and B, schilancitrilactone A, and 20-epi-schilancitrilactone A have been accomplished using a nickel-catalyzed cross coupling of alkyl bromide with vinyl stannane as the final step. The other key steps include late-stage C(sp3)-H bromination, the oxidative cleavage of a diol to provide the requisite ketone and ester for schilancidilactones A an...

A convergent total synthesis of the PP2A-inhibitor phoslactomycin A was achieved using a CuTC-mediated coupling of an alkenyl iodide C1-C13 fragment with an C14-C21 alkenyl stannane in the presence of a protected phosphate. Key features for the assembly of the C1-C13 fragment were an asymmetric dihydroxylation, an Evans-Aldol reaction, and a well-balanced protective group strategy. An asymmetri...

Here, we report a synthesis of the lower half C21-C40 fragment of the shellfish toxin, azaspiracid-1. The C28-C40 fragment was synthesized by a coupling between the C28-C35 epoxide and the C36-C40 dithioacetal anion, followed by the HI-ring spiroaminal formation. An aldehyde corresponding to the C28-C40 fragment was then coupled with the C21-C27 allylic stannane by using InCl3. Finally, the FG-...