High 1,4-syn-induction in the addition of chiral allyltrichlorostannanes to chiral aldehydes

Chiral and achiral allyltrichlorostannanes reacted with chiral aldehydes to give the corresponding homoallylic alcohols with good to high diastereoselectivities. This approach has been applied to the synthesis of hydroxyethylene dipeptide isosteres L-682, 679, L-684,414, L-685,434 and L-685,458.1024026

Synthesis of C1-C11 fragment of callystatin A

We wish to describe here our continuing efforts towards the total synthesis of the marine sponge polyketide callystatin A, describing the synthesis of the C1-C11 fragment. (C) 2002 Elsevier Science Ltd. All rights reserved.43498883888

Total synthesis of the potent antitumor polyketide (-)-callystatin A

A highly convergent and efficient total synthesis of the potent antitumor polyketide (-)-callystatin A is described. The synthesis required 19 steps from N-propionyl oxazolidinone 23 and produced the desired product in 3.5% overall yield.70124762477

Chiral allylsilane additions to chiral N-Boc-alpha-amino aldehydes

Addition of chiral allylsilane 4 to chiral N-Boc-alpha-amino aldehydes in the presence of SnCl4 in CH2Cl2 at -78 degrees C affords 1,2-syn homoallylic alcohols, potential intermediates for the synthesis of hydroxyethylene peptide isosteres. The diastereoselectivity depends on the aldehyde absolute configuration, with (R)-alpha-aminoaldehydes (matched case/anti-Felkin addition) exhibiting higher stereoselectivity than its enantiomer (mismatched case/Felkin addition).o TEXTO COMPLETO DESTE ARTIGO, ESTARÁ DISPONÍVEL À PARTIR DE AGOSTO DE 2015.1374

Synthesis of C13-C22 fragment of the marine sponged polyketide callystatin A

We wish to report here our initial efforts towards the total synthesis of callystatin A, describing the synthesis of the C13-C22 fragment. This asymmetric approach uses an efficient syn-aldol reaction, and a diastereoselective epoxidation of an allylic alcohol with m-CPBA followed by epoxide opening with Me2CuLi. (C) 2002 Elsevier Science Ltd. All rights reserved.43218518

NMR study on ligand exchange reaction between a chiral allylsilane and SnCl4

[GRAPHICS] A spectroscopic (H-1,C-13, and Sn-119 NMR) study of the reaction of chiral allylsilane 1 with SnCl4 is described. We have found that the ligand exchange between SnCl4 and this allylsilane is instantaneous and quantitative at 25 degrees C as well as at -60 degrees C, affording the corresponding allyltrichlorostannane.191335133

Stereoselective heck-matsuda arylations of chiral dihydrofurans with arenediazonium tetrafluoroborates; An efficient enantioselective total synthesis of (-)-isoaltholactone

The Heck-Matsuda arylation of chiral 2-(S)-hydroxymethyl dihydrofurans (endocyclic enolethers) and its derivatives, employing arenediazonium tetrafluoroborates, was developed into a highly efficient, practical and diastereoselective synthetic process. This methodology was applied to the total synthesis of the styryllactone (-)-isoaltholactone in seven steps with an overall yield of similar to 25%, from the readily available chiral 2-hydroxymethyldihydrofuran. The strategy permits the synthesis of several other aromatic analogues of isoaltholactone.152279228