The field of organosilicon chemistry has a position as a mainstay of modern synthetic chemistry. The series includes contributions from some of the leading practitioners in the area, covering a wide range of topics such as the stereoselective construction of oxygen and nitrogen-containing heterocycles, the use of tethered silicon reagents to deliver acyclic stereocontrol, chiral-at-silicon reagents for asymmetric synthesis, new methods for the electrochemical generation of silyl cations, allylation chemistry, and stereoselective fluorination.
Graphical Abstract
Scheme 1: Retrosynthetic analysis for the homopterocarpan skeleton.
Scheme 2: Reagents: i CH2 = CHCH2SiMe2Cl, Et3N, DCM, 85%; ii 2nd generation Grubbs catalyst, DCM, 91%.
Scheme 3: Reagents: i: BF3·Et2O (1 eq), MeOH 95%; ii: substituted benzaldehydes, BF3·Et2O (1 eq), DCM; iii: s...
Scheme 4: Reagents: i: a) OsO4, KIO4, THF-H2O, 79%; b) LiAlH4, Et2, 0°C, 76%; iii: PPh3, DIAD, THF, 70%.
Graphical Abstract
Scheme 1: Synthesis using a Temporary Connection Strategy.
Scheme 2: Intramolecular allylation of aldehyde 1 generates two out of the four possible oxasilacycles. The b...
Scheme 3: The effect of introducing a methyl group α- to the aldehyde in the cyclisation precursor will depen...
Scheme 4: Retrosynthesis of aldehyde anti-4.
Scheme 5: Attempts to reduce the bulky aryl ester resulted in Si-O bond cleavage and over-reduction to the pr...
Scheme 6: Preparation of syn- and anti-β-hydroxy esters.
Scheme 7: Preparation of the syn- and anti-aldehyde cyclisation precursors 4.
Scheme 8: Intramolecular allylation results.
Figure 1: nOe data for the two oxasilacycles obtained from allylation of aldehyde anti-4b.
Graphical Abstract
Scheme 1: Electrochemical generation of carbocations by oxidative C-C bond dissociation.
Scheme 2: Electrochemical generation and accumulation of organosilicon cation by oxidative Si-Si bond dissoci...
Figure 1: Oxidation potentials (Ed; decomposition potential) of disilanes determined by rotating disk electro...
Figure 2: Optimized structures of radical cations of 1,2-diphenyldisilane and 1,2-bis [o-(2-pyridyl)- phenyl]...
Scheme 3: Electrochemical generation of organosilicon cation 3d.
Figure 3: CSI-MS of organosilicon cation 3d at 0°C.
Figure 4: Optimized structures of organosilicon cation 3d and silyl radical 4d by DFT calculations (B3LYP/LAN...
Scheme 4: Reaction of organosilicon cation 3d with p-tolylmagnesium bromide.
Graphical Abstract
Scheme 1: [3 + 3] Annelation approach to indolizidine skeleta.
Scheme 2: Enantiospecific aziridine synthesis (ADDP: 1,1'-(azodicarbonyl)dipiperidine).
Scheme 3: Diastereoselective aldol addition.
Scheme 4: Indolizidinone formation.
Scheme 5: Preparation of a functionalised indolizidine.
Graphical Abstract
Figure 1: Cyclic and acyclic sterically encumbered silanes.
Scheme 1: Cyclic and acyclic chiral silanes as potent reagents for the silicon-to-carbon chirality transfer.
Scheme 2: Kinetic resolution of secondary alcohols using a dehydrogenative coupling reaction.
Scheme 3: Catalytic cycle for hydrosilylation.
Scheme 4: Postulated catalytic cycle for dehydrogenative coupling.
Graphical Abstract
Scheme 1: The silylcupration of allenes.
Scheme 2: Silylcupration of 1,2-propadiene and reaction with oxo compounds.
Scheme 3: Silicon assisted cyclization of oxoallylsilanes.
Scheme 4: Silylcupration of terminal alkynes bearing electron-withdrawing functions.
Scheme 5: The acid-catalyzed cyclization of epoxyallylsilanes.
Scheme 6: Intramolecular cyclization of TMS-epoxyallylsilanes.
Scheme 7: Spiro-cyclopropanation from oxoallylsilanes.
Scheme 8: Cyclobutane formation from hydroxy-functionalized allysilanes.
Scheme 9: Cyclobutene formation from vinyltin cuprates and epoxides.
Scheme 10: Silylcupration of 1,2-propadiene and reaction with α,β-unsaturated nitriles.
Scheme 11: Cycloheptane formation from silylcupration of α,β-unsaturated imines.
Scheme 12: Seven membered ring formation from functionalized allylsilanes.
Graphical Abstract
Scheme 1: Saigo's cycloisomerisation reaction under Pauson-Khand conditions.
Scheme 2: Pauson-Khand reaction and tether-cleavage in wet acetonitrile.
Scheme 3: Silyl-tethered allenic Pauson-Khand reaction reported by Brummond.
Scheme 4: Intramolecular Pauson-Khand reaction of allyldimethyl- and allyldiphenylsilyl propargyl ethers repo...
Scheme 5: Synthesis and attempted Pauson-Khand reactions of vinyldimethylsilyl- and vinyldiphenylsilyl ethers....
Figure 1: Functionalised acetylenes prepared and used in silyl ether-tethered Pauson-Khand reactions. Yields ...
Figure 2: Chain-functionalised acetylenes prepared and used in silyl ether-tethered Pauson-Khand reactions. Y...
Figure 3: Possible structure of THF-oxidation/insertion product.
Scheme 6: Model Pauson-Khand reaction of allyltrimethylsilane.
Scheme 7: Preparation of allyldiisopropylsilyl ethers.
Scheme 8: Pauson-Khand reaction of allyldiisopropylsilyl ethers.
Scheme 9: Preparation of allyldiisopropylsilanes.
Scheme 10: Attempted Mitsunobu reactions of diisopropylsilanols.
Scheme 11: Preparation of alkynic diisopropylsilanes.
Scheme 12: Preparation of allyldiisopropylsilyl ethers.
Scheme 13: Preparation of acetals from dichlorodiphenylsilane.
Scheme 14: Attempted Pauson-Khand reaction of allylpropargyldiphenylsilyl acetal.
Scheme 15: Proposed diisopropylsilyl acetal formation.
Scheme 16: Attempted allylpropargyldiisopropylsilyl acetal formation.
Scheme 17: Attempted allylpropargyldiisopropylsilyl acetal formation.
Scheme 18: Preparation of silicon-tethered Pauson-Khand precursors.
Scheme 19: Failed Pauson-Khand reaction of a silicon-tethered substrate.
Graphical Abstract
Scheme 1: Fluorination of branched allylsilanes A and B
Scheme 2: Fluorination of anti (E)-1e
Scheme 3: Double electrophilic fluorination of (E)-4
Scheme 4: Conversion of 3 into diol 7