- Formal synthesis of (±)-peduncularine: Use of the [3 + 2] annulation of allylic silanes and chlorosulfonyl isocyanate
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(equation presented) The formal synthesis of the alkaloid (±)-peduncularine (1) was accomplished through the use of a [3 + 2] allylic silane annulation. The annulation of cyclohexadienyl silane 6 with chlorosulfonyl isocyanate followed by an in situ reduction provided bicyclic lactam 7. Conversion of this intermediate to 2 in three steps completed the formal synthesis of (±)-peduncularine.
- Roberson, Claudia W.,Woerpel
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- Friedel-Crafts alkylation of benzene with (polychloromethyl)silanes
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(Polychloromethyl)silanes (Cl3-mMemSiCH3-nCln: m=0-3; n=2, 3) reacted with excess benzene in the presence of aluminum chloride to give (polyphenylmethyl)silanes. Such reactions occurred at the temperatures ranging from room temperature (m=2, 3; n=2) to 80°C (m=0, 1; n=2, 3), indicating that the reactivity increases with increasing the number (m) of electron-donating methyl-group(s) at the silicon. In particular, (dichloromethyl)silanes with two or three methyl groups at the silicon (m=2 or 3; n=2) underwent the alkylation and the decomposition of their products at room temperature. The reaction with (dichloromethyl)trimethylsilane occurred immediately at room temperature to give no (diphenylmethyl)trimethylsilane, but diphenylmethane and trimethylchlorosilane via the decomposition of alkylation product. (Trichloromethyl)silanes (m=0, 1; n=3) reacted with excess benzene to give (triphenylmethyl)silanes as major products and the unusual (diphenylmethyl)silanes as minor. It was found that unusual (diphenylmethyl)silanes were formed by the decomposition of (triphenylmethyl)silanes under the reaction condition. In the alkylation to benzene, the reactivity of (polychloromethyl)silanes (Cl3-mMemSiCH3-nCln: m=0-3; n=2, 3) decreases in the following order: m=3>2>1>0; n=3>2.
- Yoo, Bok Ryul,Kim, Jeong Hyun,Cho, Bong Gwan,Jung, Il Nam
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- Benzhydryldimethylsilyl allylic silanes: Syntheses and applications to [3 + 2] annulation reactions
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(Matrix Presented) A new silyl group, the benzhydryldimethylsilyl group, has been developed that is easily synthesized and that undergoes facile oxidation. The [3 + 2] annulation reactions of allylic silanes with this silyl group provide a variety of high
- Peng, Zhi-Hui,Woerpel
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p. 1379 - 1381
(2007/10/03)
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- 1H-CIDNP During the Reaction of Heavy Carbene Analogues R2M (M = Si, Ge, Sn; R = Me, n-Bu) with Halides
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During the reaction of photochemically generated silylenes Me2Si: with PhCH2Cl, PhCH2Br, and Ph2CHCl, 1H-CIDNP is observed in the products of insertion reactions into the C-X bonds (X = Cl, Br) and in the abstraction products Ms2SiX2 indicating the occurrence of a radical abstraction-recombination reaction.The silylenes react from singlet states.Me2Si: reacts with CH2=CHCH2Cl without CIDNP phenomena in a concerted way. (n-Bu2Sn)6 reacts with EtBr via a radical chain mechanism without the appearance of free stannylenes n-Bu2Sn: as intermediates.
- Lehnig, Manfred,Klaukien, Heino,Reininghaus, F.
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p. 1411 - 1414
(2007/10/02)
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