106357-29-3Relevant 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.
The total synthesis of scytophycin C. Part 1: Stereocontrolled synthesis of the C1-C32 protected seco acid
Paterson, Ian,Yeung, Kap-Sun,Watson, Christine,Ward, Richard A.,Wallace, Paul A.
, p. 11935 - 11954 (2007/10/03)
A stereocontrolled synthesis of the C1-C32 seco acid derivative 9 for scytophycin C (1) was completed in 14 steps (18.2% yield, 85% ds) from aldehyde (S)-18. Key steps include: (i) the asymmetric crotylboration of (S)- 18 to give hom
Studies in marine macrolide synthesis: A stereocontrolled synthesis of a C17- C32 subunit of scytophycin C
Paterson, Ian,Yeung, Kap-Sun
, p. 5347 - 5350 (2007/10/02)
The C17-C32 subunit 8 of scytophycin C was prepared in 11 steps (19% yield, 83% ds) from (S)-12. Key features include the dipropionate aldol construction of the stereopentad 11, the Brown asymmetric crotylboration leading to 10, followed by their Ba(OH)2-induced, Horner-Emmons coupling to give 23, and the BF3·OEt2-promoted allylation, 25 → 26.
Acyclic diastereoselective synthesis using tartrate ester modified crotylboronates. Double asymmetric reactions with α-methyl chiral aldehydes and synthesis of the C(19)-C(29) segment of rifamycin S
Roush, William R.,Palkowitz, Alan D.,Ando, Kaori
, p. 6348 - 6359 (2007/10/02)
Double asymmetric reactions of the tartrate ester modified crotylboronates 1 and 2 and α-methyl chiral aldehydes are described. The reactions of the appropriate enantiomers of 1 and 2 with β-alkoxy-α-methylpropionaldehydes 11 provide adducts 12, 13, and 1
Chiral Synthesis via Organoboranes. 21. Allyl- and Crotylboration of α-Chiral Aldehydes with Diisopinocampheylboron as the Chiral Auxiliary
Brown, Herbert C.,Bhat, Krishna S.,Randad, Ramnarayan S.
, p. 1570 - 1576 (2007/10/02)
B-Allyldiisopinocampheylboranes have been screened for diastereofacial selectivity in their reaction with α-substituted chiral aldehydes.Both syn and anti products have been obtained in very high diastereoselectivities.Further, (E)-crotyldiisopinocampheylboranes and (Z)-crotyldiisopinocampheylboranes have been used for diastereofacial selectivity in their reaction with α-substituted chiral aldehydes.These crotylboranes, 20-23, are highly diastereoselective reagents and the corresponding (3,4- and 4,5-)-anti,syn, -anti,anti, and -syn,anti products have been obtained in very high facial selectivities; even the syn,syn product has been obtained in moderately good facial selectivity.Finally, the relative efficiences of the various chiral auxiliaries utilized in the literature for the allyl- and crotylboration have been compared with those achieved by the diisopinocampheylboron moiety.
