Bifunctional conjunctive reagents: 5-chloro-2-lithio-1-pentene and related substances. A methylenecyclohexane annulation method

1993 ◽  
Vol 71 (3) ◽  
pp. 280-286 ◽  
Author(s):  
Edward Piers ◽  
Bik Wah Anissa Yeung ◽  
Fraser F. Fleming
Keyword(s):  
Grignard Reagent ◽  
Conjugate Addition ◽  
The Novel ◽  
Intramolecular Alkylation ◽  
Related Substances ◽  
Cyclic Enones

The development of a new, synthetically useful methylenecyclohexane annulation method is described. Transmetallation (MeLi, tetrahydrofuran, −78 °C) of 5-chloro-2-trimethylstannyl-1-pentene (8) affords the novel bifunctional reagent 5-chloro-2-lithio-1-pentene (9), which, at temperatures higher than approximately −50 °C, self-destructs to give methylenecyclobutane (14). Reagent 9 can be converted into the Grignard reagent 10 and the organocopper(I) species 15. Conjugate addition of 10 and 15 to a number of cyclic enones (16–22), followed by intramolecular alkylation of the resultant adducts (23–29), produces the corresponding methylenecyclohexane annulation products (30–40).

Annulation via donor-acceptor reagents. An efficient total synthesis of (±)-∆9(12)-capnellene

1984 ◽  
Vol 62 (3) ◽  
pp. 629-631 ◽  
Author(s):  
E. Piers ◽  
V. Karunaratne
Keyword(s):  
Total Synthesis ◽  
Grignard Reagent ◽  
Conjugate Addition ◽  
Intramolecular Alkylation ◽  
Racemic Form ◽  
Donor Acceptor ◽  
Key Steps

A short, efficient total synthesis of the racemic form of the marine sesquiterpenoid (-)-∆9(12)-capnellene (1) is described. The key steps of the synthesis are two methylenecyclopentane annulation sequences (14 → 16; 22 → 24) involving the CuBr-Me2S→BF3 • Et2O catalyzed conjugate addition of the Grignard reagent 13 to the enones 14 and 22, followed by intramolecular alkylation (KH, tetrahydrofuran) of the resultant adducts 15 and 23, respectively

A practical asymmetric conjugate addition to cyclic enones with chiral bifunctional Ru amido catalysts

2012 ◽  
Vol 53 (27) ◽  
pp. 3452-3455 ◽  
Author(s):  
Pavel A. Dub ◽  
Hui Wang ◽  
Masahito Watanabe ◽  
Ilya D. Gridnev ◽  
Takao Ikariya
Keyword(s):  
Conjugate Addition ◽  
Cyclic Enones

ChemInform Abstract: Enantioselective One-Pot Conjugate Addition of Grignard Reagents to Cyclic Enones Followed by Amidomethylation.

ChemInform ◽  
2012 ◽  
Vol 43 (18) ◽  
pp. no-no
Author(s):  
Filip Bilcik ◽  
Michal Drusan ◽  
Jozef Marak ◽  
Radovan Sebesta
Keyword(s):  
Conjugate Addition ◽  
Grignard Reagents ◽  
One Pot ◽  
Cyclic Enones

Enantioselective Organocatalytic Construction of Carbocycles: The Nicolaou Synthesis of Biyouyanagin A

2011 ◽  
Author(s):  
Douglass Taber
Keyword(s):  
Methyl Ether ◽  
Conjugate Addition ◽  
Unsaturated Aldehyde ◽  
Enantiomerically Pure ◽  
Intramolecular Alkylation ◽  
Stereogenic Centers ◽  
Chinese Academy Of Sciences ◽  
Academy Of Sciences ◽  
Polycyclic System ◽  
Selective Addition

One of the more powerful routes to enantiomerically-pure carbocycles is the desymmetrization of a prochiral ring. Karl Anker Jørgensen of Aarhus University has found (J. Am. Chem. Soc. 2007, 129, 441) that many cyclic β-ketoesters, including the vinylogous carbonate 1, can be homologated with 2 to the corresponding alkyne 3, in high ee. Sanzhong Luo of the Chinese Academy of Sciences, Beijing, and Jin-Pei Cheng, of the Chinese Academy of Sciences and Nankai University, have shown (J. Org. Chem. 2007, 72, 9350) that the catalyst 6 mediated the selective addition of 4-substituted cyclohexanones such as 4 to the nitroalkene 5, establishing three new stereogenic centers. Organocatalysts, alone or complexed with activating metals, have also been used to effect enantioselective ring construction. E. J. Corey of Harvard University has established (J. Am. Chem. Soc. 2007, 129, 12686) that the proline-derived complex 10 will mediate the 2 + 2 addition of a cyclic enol ether with an acrylate to give the cyclobutane 11. Further elaboration led to the cyclohexenone 12. Armando Córdova of Stockholm University has described (Tetrahedron Lett. 2007, 48, 5835) a novel route to cyclopentanones such as 16, via tandem conjugate addition/intramolecular alkylation. Professor Jørgensen has reported (Angew. Chem. Int. Ed . 2007, 46 , 9202) the double addition of 18 to the unsaturated aldehyde 17 to give 20. Earlier last year, Yujiro Hayashi of the Tokyo University of Science had shown (Angew. Chem. Int. Ed. 2007, 46, 4922) that the double addition of the inexpensive 21 to 5 could, depending on conditions, be directed selectively to 22, 23, or 24. As illustrated by the conversion of 8 to 13, organocatalysis can be used to effect the enantioselective construction of polycarbocyclic products. The initial ring prepared in enantiomerically-pure form by organocatalysis can also set the chirality of a polycyclic system. Professor Corey has reported (J. Am. Chem. Soc. 2007, 129, 10346) that Itsuno-Corey reduction of the prochiral diketone 25 led to the ketone 27. Cyclization followed by oxidation and reduction then delivered estrone methyl ether 28.

Aprotic conjugate addition of allyllithium reagents bearing polar groups to cyclic enones. 1. 3-Alkylallyl systems

1988 ◽  
Vol 110 (16) ◽  
pp. 5411-5423 ◽  
Author(s):  
Malcolm R. Binns ◽  
Richard K. Haynes ◽  
Andrew G. Katsifis ◽  
Paul A. Schober ◽  
Simone C. Vonwiller
Keyword(s):  
Conjugate Addition ◽  
Polar Groups ◽  
Cyclic Enones

Aprotic Conjugate Addition Reactions of Lithiated Allylic Sulfoxides With Acyclic Enones; a Breakdown of the trans-Decalyl Transition State

1989 ◽  
Vol 42 (10) ◽  
pp. 1785 ◽  
Author(s):  
RK Haynes ◽  
AG Katsifis ◽  
LM King ◽  
SC Vonwiller
Keyword(s):  
Transition State ◽  
Conjugate Addition ◽  
Vinyl Ketone ◽  
Methyl Vinyl Ketone ◽  
Mesityl Oxide ◽  
Addition Reactions ◽  
State Characteristic ◽  
Methyl Vinyl ◽  
Cyclic Enones ◽  
Carbonyl Addition

The reactions of lithiated 1-(t-butylsulfinyl)prop-2-ene, 1-(t-butylsulfinyl)-3-methylbut-2-ene, 1-(t-butylsulfinyl)but-2-ene, 1-(phenylsulfinyl)but-2-ene and 2-methyl-1-(phenylsu1finyl)prop- 2-ene with methyl vinyl ketone, mesityl oxide and crotonaldehyde give largely carbonyl addition products arising from reaction through C1 or C3 of the allyl system. In the case of methyl crotonate, conjugate addition through C3 is observed. The initially formed diastereomers of the C1 adducts, allylic sulfoxides, are configurationally unstable. Only the lithiated 1-(t-butylsulfinyl)-3-methylbut-2-ene undergoes conjugate addition with methyl vinyl ketone to give an (E)-vinyl sulfoxide whose formation may involve the trans-decalyl transition state characteristic of the reactions of lithiated allylic sulfoxides with cyclic enones.

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