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US5231205A
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Preparation and use of (2-butene-1,4-diyl)magnesium complexes in organic synthesis
Assignee: University of Nebraska System
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Filing: 1991-09-23
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Granted: 1993-07-27
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Expires: 2011-09-23
Abstract
Abstract The magnesium complexes of cyclic hydrocarbons, such as 1,2-dimethylenecycloalkanes, are readily prepared in high yields using highly reactive magnesium. Reactions of these (2-butene-1,4-diyl)magnesium reagents with electrophiles such as dibromoalkanes, alkylditosylates, or bromoalkylnitriles serve as a convenient method for synthesizing spirocyclic systems. Significantly, spirocarbocycles prepared by this method contain functional groups such as the exocyclic double bond or a keto group in one of the rings which could be used for further elaboration of these molecules. Furthermore, fused bicyclic systems containing a substituted five-membered ring can be conveniently prepared at high temperatures by the reactions of (2-butene-1,4-diyl)magnesium complexes with carboxylic esters and acids whereas low temperatures lead to regioselective synthesis of beta , gamma -unsaturated ketones.
Inventors
- 👤 Reuben D. Rieke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:47
CPC Classifications
C; C07; C07C; C07C17/00; C07C17/26; C07C17/263; C07B; C07B37/00; C07B37/10; C07B49/00; C07C17/2632; C07C255/00; C07C255/01; C07C255/31; C07C29/00; C07C29/36; C07C29/38; C07C29/40; C07C45/00; C07C45/004; C07C45/45; C07C49/00; C07C49/20; C07C49/21; C07C49/587; C07C49/647; C07C49/653; C07C49/76; C07C49/794; C07C49/798; C07D; C07D307/00; C07D307/94; C07F; C07F3/00; C07F3/02; C07F7/00; C07F7/02; C07F7/08; C07F7/0803; C07F7/0805; C07F7/0807; C07F7/081; C07F7/0825; C07F7/0827; C07F7/22; C07F7/2208; C07F7/24; C07F7/26; C07F7/30; C07C2601/00; C07C2601/12; C07C2601/14; C07C2602/00; C07C2602/02; C07C2602/14; C07C2602/22; C07C2602/24; C07C2602/26; C07C2602/30
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
79 words
A method for the preparation of spirocycles comprising: a. contacting a magnesium(II) salt in an ethereal, polyethereal, or hydrocarbon solvent with a reducing agent having a reduction potential of about -1.5 volts, or more negative, to form a highly reactive magnesium species; b. contacting the highly reactive magnesium species with a cyclic hydrocarbon containing at least two conjugated exocyclic double bonds to form a (2-butene-1,4-diyl)magnesium complex; and c. contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile to form a spirocycle.
Claim 2
Independent Claim
79 words
A method for the preparation of spirocycles comprising: a. contacting a magnesium(II) salt in an ethereal, polyethereal, or hydrocarbon solvent with a reducing agent having a reduction potential of about -1.5 volts, or more negative, to form a highly reactive magnesium species; b. contacting the highly reactive magnesium species with a cyclic hydrocarbon containing at least two conjugated exocyclic double bonds to form a (2-butene-1,4-diyl)magnesium complex; and c. contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile to form a spirocycle.
Claim 3
Dependent Claim
21 words
The method of claim 1 wherein the electrophiles are selected from the group consisting of organodihalides, organoditosylates, haloalkylnitriles, esters, and amides.
Claim 4
Dependent Claim
19 words
The method of claim 2 wherein the electrophiles are selected from the group consisting of alkyldibromides, alkylditosylates, and bromoalkylnitriles.
Claim 5
Dependent Claim
26 words
The method of claim 1 wherein the step of contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile is carried out at a temperature below about 100° C.
Claim 6
Dependent Claim
25 words
The method of claim 2 wherein the step of contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile is carried out in an ethereal or polyethereal solvent.
Claim 7
Dependent Claim
24 words
The method of claim 1 wherein the solvent used in the preparation of the highly reactive magnesium species is an ethereal or polyethereal solvent.
Claim 8
Dependent Claim
10 words
The method of claim 6 wherein the solvent is tetrahydrofuran.
Claim 9
Dependent Claim
28 words
The method of claim 1 wherein the reducing agent used in the preparation of the highly reactive magnesium species is an alkali metal salt of an aromatic anion.
Claim 10
Dependent Claim
23 words
The method of claim 8 wherein the reducing agent is selected from the group consisting of sodium or lithium naphthalenide, anthracenide, or biphenylide.
Claim 11
Dependent Claim
13 words
The method of claim 9 wherein the reducing agent is preformed lithium naphthalenide.
Claim 12
Dependent Claim
18 words
The method of claim 1 wherein the cyclic hydrocarbon is a cycloalkane containing two conjugated exocyclic double bonds.
Claim 13
Dependent Claim
19 words
The method of claim 11 wherein the cycloalkane is selected from the group consisting of 1,2-dimethylenecyclohexane, 1,2-dimethylenecyclopentane, and 1,2-dimethylenecycloheptane.
Claim 14
Dependent Claim
28 words
The method of claim 1 wherein the step of contacting the highly reactive magnesium species with a cyclic hydrocarbon is carried out in an ethereal or polyethereal solvent.
Claim 15
Independent Claim
80 words
A method for the preparation of spirocycles comprising: a. contacting a magnesium(II) salt in an ethereal, polyethereal, or hydrocarbon solvent with an alkali metal salt of an aromatic anion to form a highly reactive magnesium species; b. contacting the highly reactive magnesium species with a cyclic hydrocarbon containing at least two conjugated exocyclic double bonds to form a (2-butene-1,4-diyl)magnesium complex; and c. contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile at a temperature below about 100° C. to form a spirocycle.
Claim 16
Independent Claim
80 words
A method for the preparation of spirocycles comprising: a. contacting a magnesium(II) salt in an ethereal, polyethereal, or hydrocarbon solvent with an alkali metal salt of an aromatic anion to form a highly reactive magnesium species; b. contacting the highly reactive magnesium species with a cyclic hydrocarbon containing at least two conjugated exocyclic double bonds to form a (2-butene-1,4-diyl)magnesium complex; and c. contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile at a temperature below about 100° C. to form a spirocycle.
Claim 17
Dependent Claim
34 words
The method of claim 14 wherein the alkali metal salt of an aromatic anion is selected from the group consisting of sodium naphthalenide, sodium anthracenide, sodium biphenylide, lithium naphthalenide, lithium anthracenide, and lithium biphenylide.
Claim 18
Dependent Claim
17 words
The method of claim 15 wherein the alkali metal salt of an aromatic anion is lithium naphthalenide.
Claim 19
Independent Claim
103 words
A method for the preparation of spirocycles comprising: a. contacting a magnesium(II) salt in an ethereal, polyethereal, or hydrocarbon solvent with a reducing agent having a reduction potential of about -1.5 volts, or more negative, to form a highly reactive magnesium species, wherein the reducing agent is an alkali metal salt of an aromatic anion; b. contacting the highly reactive magnesium species with a cycloalkane containing at least two conjugated exocyclic double bonds to form a (2-butene-1,4-diyl)magnesium complex; and c. contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile selected from the group consisting of organodihalides, organoditosylates, haloalkylnitriles, esters, and amides to form a spirocycle.
Claim 20
Independent Claim
103 words
A method for the preparation of spirocycles comprising: a. contacting a magnesium(II) salt in an ethereal, polyethereal, or hydrocarbon solvent with a reducing agent having a reduction potential of about -1.5 volts, or more negative, to form a highly reactive magnesium species, wherein the reducing agent is an alkali metal salt of an aromatic anion; b. contacting the highly reactive magnesium species with a cycloalkane containing at least two conjugated exocyclic double bonds to form a (2-butene-1,4-diyl)magnesium complex; and c. contacting the (2-butene-1,4-diyl)magnesium complex with an electrophile selected from the group consisting of organodihalides, organoditosylates, haloalkylnitriles, esters, and amides to form a spirocycle.
Claim 21
Dependent Claim
29 words
The method of claim 17 wherein the reducing agent is selected from the group consisting of sodium naphthalenide, sodium anthracenide, sodium biphenylide, lithium naphthalenide, lithium anthracenide, and lithium biphenylide.
Claim 22
Dependent Claim
20 words
The method of claim 17 wherein the Mg(II) salt is a Mg(II) salt of sulfate, nitrate, nitrite, cyanide, or halide.
Claim 23
Dependent Claim
13 words
The method of claim 19 wherein the Mg(II) salt is MgCl 2 .
References Cited (Backward Citations)
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