108393-30-2Relevant academic research and scientific papers
Synthesis of polypropionate subunits from cyclopropanes
Defosseux, Magali,Blanchard, Nicolas,Meyer, Christophe,Cossy, Janine
, p. 7632 - 7653 (2007/10/03)
The oxymercuration-reductive demercuration of several cyclopropanealkanol or their derivatives bearing adjacent stereocenters has been investigated in order to synthesize polypropionate subunits. The crucial importance of the ester protecting group for th
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.
Total synthesis of scytophycin C. 1. Stereoselective syntheses of the C(1)-C(18) segment and the C(19)-C(31) segment
Nakamura, Ryoichi,Tanino, Keiji,Miyashita, Masaaki
, p. 3579 - 3582 (2007/10/03)
[Equation presented] Stereoselective total synthesis of scytophycin C, a marine 22-membered macrolide displaying potent activity against a variety of human carcinoma cell lines, has been reported in which the polypropionate structure bearing contiguous as
Synthesis of stereotriads by oxymercuration of substituted cyclopropylcarbinols.
Cossy,Blanchard,Meyer
, p. 2567 - 2569 (2007/10/03)
[structure: see text] Cyclopropylcarbinol derivatives bearing an adjacent methyl-substituted stereocenter and a remote beta-hydroxy group protected as a pivalate underwent anchimerically assisted regio- and diastereoselective oxymercurations, affording af
Regioselective Alkyl and Alkynyl Substitution Reactions of Epoxy Alcohols by the Use of Organoaluminum Ate Complexes: Regiochemical Reversal of Nucleophilic Substitution Reactions
Sasaki, Minoru,Tanino, Keiji,Miyashita, Masaaki
, p. 1765 - 1767 (2007/10/03)
(matrix presented) Unprecedented nucleophilic substitution reactions of 2,3-epoxy-1-alkanols with alkyl- and alkynylaluminum ate complexes have been studied and demonstrated to occur at the C2 position with extremely high stereoselectivity, i.e., with exa
Stereoselective Total Synthesis of (+/-)-Invictolide. An Efficient Preparation of a Trisubstituted δ-Lactone from Aldol Precursors
Pilli, Ronaldo Aloise,Murta, Maria Marcia
, p. 338 - 342 (2007/10/02)
The stereoselective total synthesis of (+/-)-invictolide (1), a component of the queen recognition pheromone of Solenopsis invicta, is described.The TiCl4-mediated addition of silyl ketene thioacetal 8 to (+/-)-3-(benzyloxy)-2-methylpropionaldehyde afford
Pheromone Synthesis, CXXXV. Synthesis of (4R,5R,6S,7E,9E)-4,6,8-Trimethyl-7,9-undecadien-5-ol and Its Antipode, the Female Specific Compound of the Woodroach Cryptocercus punctulatus
Mori, Kenji,Itou, Masamichi
, p. 87 - 94 (2007/10/02)
(4R,5R,6S,7E,9E)-4,6,8-Trimethyl-7,9-undecadien-5-ol (1) and its antipode 1', the female specific compound of the woodroach Cryptocercus punctulatus, were synthesized by starting from methyl (R)-3-hydroxy-2-methylpropanoate (C). Key Words: Chiral centers,
Diastereoselective Synthesis of 2,3-anti-5-Benzyloxy-2,4-dimethyl-1,3-pentanediols via Cyclic Hydroboration
Yokoyama, Yasushi,Terada, Yuji,Kawashima, Hideyuki
, p. 2563 - 2565 (2007/10/02)
The treatment of (2E,4S)- and (2Z,4S)-1-benzyloxy-5-ethenyloxy-2,4-dimethyl-2-pentene with borane both with and without a catalytic amount of Rh(Ph3P)3Cl gave 2,3-anti-3,4-anti-(2R,3R,4S)- and 2,3-anti-3,4-syn-(2R,3R,4R)-5-benzyloxy-2,4-dimethyl-1,3-penta
Calyculin synthetic studies. 2. Stereocontrolled assembly of the C(9)-C(13) dithiane and C(26)-C(37) oxazole intermediates
Smith III, Amos B.,Salvatore, Brian A.,Hull, Kenneth G.,Duan, James J.-W.
, p. 4859 - 4862 (2007/10/02)
The C(9)-C(13) dithiane (+)-2 and C(26)-C(37) γ-amino acid/oxazole (+)-5, key building blocks for calyculin total synthesis, have been elaborated in homochiral form. Noteworthy features of the schemes include stereocontrolled generation of the C(36) steeo
TiCl4-Mediated Reactions of the Silyl Ketene Acetals Derived from N-Methylephedrine Esters: An Asymmetric Variant of the Mukaiyama Reaction
Gennari, Cesare,Colombo, Lino,Bertolini, Giorgio,Schimperna, Giuliana
, p. 2754 - 2760 (2007/10/02)
The TiCl4-mediated reaction between silyl ketene acetals 2 and benzaldehyde was chosen as a model for mechanistic studies.The influence of the silyl ketene acetal double-bond geometry, the C-1/C-2 relative configuration of N-methylephedrine, and different modes of addition and molar ratios of reagents on the stereochemical outcome of the reaction was investigated.On the basis of these results and of literature data, an octahedral, six-coordinate titanium complex was proposed as the transition-structure model.This model helps to rationalize some of the experimental data (e.g., the anti-syn ratios with aldehydes and imines).The TiCl4-mediated additions of the E silyl ketene acetal derived from (1R,2S)-N-methylephedrine propionate 1 (R=Me) to racemic 3-(benzyloxy)-2-methylpropionaldehyde (11) (kinetic resolution), (+)-(S)-11 (mismatched pair), and (-)-(R)-11 (matched pair) were studied.In the matched pair case three contiguous stereocenters were established with complete selectivity.The Mukaiyama-Michael additions of 1 (R = Me) to vinyl ketones were also studied.By this route α-methyl-δ-keto esters were obtained in 72-75 percent ee.
