Influence des groupes tert-butyle, triméthylsilyle et triméthylgermyle sur la stéréochimie de réactions d'addition en série cyclohexénique. I. Synthèse des alcènes et hydroboration

Abstract

Syntheses of 1-tert-butyl-(1a), 1-trimethylsilyl-(1b) and 1-trimethylgermanyl-4,4-dimethylcyclohexene (1c) are described as are those of 6-tert-butyl- (2a), 6-trimethylsilyl- (2b) and 6-trimethylgermanyl-3,3-dimethylcyclohexene (2c). The stereochemistry of the hydroboration of these alkenes is examined. The stereochemistry is governed, on the one hand, by the steric influence of the various substituents and on the other by the steric and electronic effects of the trimethylsilyl and trimethylgermanyl groups. [Journal translation]

Catalysis of the Addition of Benzenethiol to 2-Cyclohexen-1-ones by Uranyl-Salophen Complexes: A Catalytic Metallocleft with High Substrate Specificity

“…When this is not the case, the overall reaction rate is given by the sum of two contributions [Equation (11)]. Substitution of Equations ( 5) and (9) into Equation ( 11), followed by integration, leads to Equation (12), that again applies to the case of different reactant concentrations, and where the quantities a and b are defined in Equations ( 13) and ( 14), respectively.…”

“…However, since K E and K P are independently known, and since the composition of the mixture at any time is known from 1 H-NMR data, the left-hand terms contain k cat as the only unknown quantity. For each catalytic experiment a k cat value was selected using a computer programme such that the left side of Equation ( 10) or, whenever appropriate, Equation (12) plots against time as a straight line with unit slope and zero intercept. An example of such a plot is shown in Figure 5.…”

“…Salophen ± uranyl complexes 1 and 2 were available from a previous work. [3] 5,5-Dimethyl-2-cyclohexen-1-one (5 a), [11] 6,6-dimethyl-2-cyclohexen-1-one (6 a), [12] 3-(phenylthio)cyclohexanone (3 b), [13] and 4,4dimethyl-3-(phenylthio)cyclohexanone (4 b), [14] m.p. 61 ± 62 8C, lit.…”

New Insight into the Mechanism of the Conjugate Addition of Benzenethiol to Cyclic and Acyclic Enones and of the Corresponding Uranyl−Salophen‐Catalysed Version

“…2‐Cyclopenten‐1‐one (Aldrich) was used as received. 1‐(Phenylthio)‐3‐pentanone was prepared according to a standard literature procedure34 and showed spectroscopic data consistent with the expected structure. Salophen−uranyl complexes 1 and 2 were available from previous studies 22,23…”

Development of the [3 + 2] Annulations of Cyclohexenylsilanes and Chlorosulfonyl Isocyanate: Application to the Total Synthesis of (±)-Peduncularine

“…We envisioned that the azabicyclic core of peduncularine could be assembled in a single step using a [3 + 2] annulation reaction of a functionalized cyclohexenylsilane such as 4 with chlorosulfonyl isocyanate (eq 2). ,, These annulation reactions (including both the [3 + 2] and [2 + 2] versions) are powerful tools for the synthesis of both carbocyclic and heterocyclic rings. , The silane 4 would require a functional group suitable for introduction of the C3−C4 double bond of peduncularine. The silyl group at C-8 of annulation product 3 would be oxidized to a hydroxyl group, providing a handle for installation of the exocyclic double bond of 1 .…”