79563-31-8Relevant academic research and scientific papers
Stereocontrol in organic synthesis using silicon-containing compounds. Studies directed towards the synthesis of ebelactone A
Archibald, Sarah C.,Barden, David J.,Bazin, Jerome F.Y.,Fleming, Ian,Foster, Colin F.,Mandal, Ajay K.,Mandal, Amit K.,Parker, David,Takaki, Ken,Ware, Anne C.,Williams, Anne R.B.,Zwicky, Anna B.
, p. 1051 - 1064 (2007/10/03)
Several approaches to the synthesis of ebelactone A 2 are described, culminating in the synthesis of the benzenesulfonate of 2-epi-ebelactone A 161. All the approaches were based on three fragments A, B and C, originally defined in general terms in Scheme 1, but eventually used as the aldehyde 72, the allenylsilane 3 and the aldehyde 139, respectively. They were joined, first B with C, and then B+C with A. In the main routes to fragments A and C, the relative stereochemistry was controlled by highly stereoselective enolate methylations 66 → 67, 68 → 69, and 135 → 136, in each case anti to an adjacent silyl group, and by a highly stereoselective hydroboration of an allylsilane 137 → 138, also anti to the silyl group. The hydroxyl groups destined to be on C-3 and C-11 were unmasked by silyl-to-hydroxy conversions 69 → 70 and 138 → 139 with retention of configuration. The stereochemistry created in the coupling of fragment B to C was controlled by the stereospecifically anti SE2′ reaction between the enantiomerically enriched allenylsilane 3 and the aldehyde 139. The double bond geometry was controlled by syn stereospecific silylcupration 148 → 151, and preserved by iododesilylation 151 → 152 of the vinylsilane with retention of configuration, and Nozaki-Hiyama-Kishi coupling with the aldehyde 72 gave the whole carbon skeleton 153 of ebelactone A with the correct relative configuration, all of which had been controlled by organosilicon chemistry. In the steps to remove the superfluous allylic hydroxyl, an intermediate allyllithium species 156 abstracted the proton on C-2, and its reprotonation inverted the configuration at that atom. Other routes to the fragments A and C were also explored, both successful and unsuccessful, both silicon-based and conventional, and a number of unexpected side reactions were investigated.
Syntheses of isotopically labelled L-?±-amino acids with an asymmetric centre at C-3
Harding, John R.,Hughes, Rachael A.,Kelly, Nicholas M.,Sutherland, Andrew,Willis, Christine L.
, p. 3406 - 3416 (2007/10/03)
Approaches are described to the synthesis of a series of isotopically labelled L-a-amino acids each with an asymmetric centre at C-3, including isoleucine, allo-isoleucine, threonine and allo-threonine. The methods may be simply adapted for the selective incorporation of an isotopic label at each site of L-valine including the selective labelling of either diastereotopic methyl group with carbon-13 and/or deuterium and labelling of the amine with nitrogen-15. ? The Royal Society of Chemistry 2000.
