scholarly journals Highly Asymmetric-selective and Stereoselective Polymerization of (RS)-α-Methylbenzyl Methacrylate with Cyclohexyl-magnesium Bromide-Axially Dissymmetric 2,2′-Diamino-6,6′-dimethylbiphenyl System

1987 ◽  
Vol 19 (9) ◽  
pp. 1047-1065 ◽  
Author(s):  
Shigeyoshi Kanoh ◽  
Sakae Goka ◽  
Nobutsugu Murose ◽  
Hideo Kubo ◽  
Masao Kondo ◽  
...  
Keyword(s):  
Magnesium Bromide

Studies on the synthesis of heterocyclic compounds. XI. Cleavage of 1,3-benzodioxoles by magnesium bromide-acetic anhydride

1983 ◽  
Vol 20 (3) ◽  
pp. 703-707 ◽  
Author(s):  
Leonardo Bonsignore ◽  
Anna Maria Fadda ◽  
Giuseppe Loy ◽  
Antonio Maccioni ◽  
Gianni Podda
Keyword(s):  
Acetic Anhydride ◽  
Heterocyclic Compounds ◽  
Magnesium Bromide

Enantioselective synthesis of (R)-tolterodine using lithiation/borylation–protodeboronation methodology

2012 ◽  
Vol 90 (11) ◽  
pp. 965-974 ◽  
Author(s):  
Stefan Roesner ◽  
Varinder K. Aggarwal
Keyword(s):  
Enantioselective Synthesis ◽  
High Yield ◽  
Magnesium Bromide ◽  
Efficient Synthesis ◽  
Boronic Ester ◽  
Better Than

The synthesis of the pharmaceutical (R)-tolterodine is reported using lithiation/borylation–protodeboronation of a homoallyl carbamate as the key step. This step was tested with two permutations: an electron-neutral aryl Li-carbamate reacting with an electron-rich boronic ester and an electron-rich aryl Li-carbamate reacting with an electron-neutral boronic ester. It was found that the latter arrangement was considerably better than the former. Further improvements were achieved using magnesium bromide in methanol leading to a process that gave high yield and high enantioselectivity in the lithiation/borylation reaction. The key step was used in an efficient synthesis of (R)-tolterodine in a total of eight steps in a 30% overall yield and 90% ee.

Structural preferences for the double bond position in some unsaturated 3,3-diphenylpyrrolidines

1970 ◽  
Vol 48 (23) ◽  
pp. 3742-3745 ◽  
Author(s):  
M. M. A. Hassan ◽  
A. F. Casy
Keyword(s):  
Double Bond ◽  
Methyl Iodide ◽  
Quaternary Salt ◽  
Double Bond Position ◽  
Magnesium Bromide ◽  
Free Base ◽  
Spectroscopic Evidence ◽  
Structural Preferences ◽  
Ethyl Magnesium Bromide ◽  
Sole Product

The reaction between 3,3-diphenyl-3-cyano-1-methylpropyl isocyanate and ethyl magnesium bromide leads to 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline rather than the isomeric 2-ethylidenepyrrolidine. The protonated N-methyl analogue (identical with a major metabolite of methadone) retains the 1-pyrroline structure, but the free base is a cis-trans mixture of the corresponding 2-ethylidenepyrrolidines; the cis Me/Ph isomer preponderates and is the sole product (obtained as a quaternary salt) when the mixture is treated with methyl iodide. 5-Methyl-2-methylene-3,3-diphenylpyrrolidine, a lower homologue of the methadone metabolite, isomerizes to a 1-pyrroline derivative when protonated or methylated. All structural conclusions are based on i.r. and p.m.r. spectroscopic evidence.

Organophosphorus compounds. XII. A new synthesis of phosphindolines and phosphindoles

1974 ◽  
Vol 27 (4) ◽  
pp. 831 ◽  
Author(s):  
DJ Collins ◽  
LE Rowley ◽  
JM Swan
Keyword(s):  
Hydrochloric Acid ◽  
Zinc Chloride ◽  
Organophosphorus Compounds ◽  
Magnesium Bromide ◽  
New Synthesis

The reaction of 2-phenylethylphosphonous dichloride with zinc chloride at 170� followed by hydrolysis with concentrated hydrochloric acid, and oxidation, gave 72% of 1-hydroxyphosphindoline 1-oxide. Treatment of the derived phosphinic chloride with vinyl magnesium bromide at -40� afforded 1-vinylphosphindoline 1-oxide which underwent addition of dimethylamine to yield 1-(2'-dimethylaminoethyl)phosphindoline 1-oxide. The conversions of 1-chlorophosphindoline 1-oxide into 1-ethyl- and 1-phenyl-phosphindoline 1-oxide are described. Bromination of l-methoxy- phosphindoline 1-oxide with N-bromosuccinimide followed by dehydrobromination afforded 1-methoxyphosphindole 1-oxide. 1-(2'-Dimethylaminoethyl)phosphindoline 1-oxide and the corresponding phosphine sulphide were assayed for analgetic activity.

The Baran Synthesis of Ingenol

2017 ◽  
Author(s):  
Douglass F. Taber
Keyword(s):  
Claisen Rearrangement ◽  
Secondary Alcohol ◽  
Cyclic Carbonate ◽  
The Other ◽  
Magnesium Bromide ◽  
Pseudomonas Cepacia ◽  
Pinacol Rearrangement ◽  
Pseudomonas Cepacia Lipase ◽  
La Jolla ◽  
Open Face

The early promise for the biological activity of the derivatives of ingenol 3 has been borne out by the clinical efficacy of the derived angelate, recently approved by the US Food and Drug Administration for the treatment of actinic keratosis. Phil S. Baran of Scripps La Jolla envisioned (Science 2013, 341, 878) a route to 3 based on a rearrange­ment of 2, available by the Pauson–Khand cyclization of the allenyl alkyne 1. One of the partners for the preparation of 1 was available following the Sugai (Synlett 1997, 1297) procedure, by the Claisen rearrangement of triethyl orthopro­pionate 5 with the propargyl alcohol 4 to give 6. Reduction delivered a racemic mix­ture of alcohols. On exposure of the mixture to vinyl acetate and Pseudomonas cepacia lipase, the undesired enantiomer was selectively acetylated to 7, leaving residual 8 of high ee. IBX was found by the Scripps group to be effective at oxidizing 8 without racemization. The other component of 1 was prepared from the inexpensive (+)-3-carene 10. Chlorination followed by ozonolysis delivered 11, that was reduced to the enolate, then alkylated with methyl iodide. Exposure to LiHMDS gave a new enolate, that was added to the aldehyde 9 to give 12. Addition of ethynyl magnesium bromide to the now more open face of 12 proceeded with high diastereoselectivity. Selective silylation of the secondary alcohol followed by silylation of the tertiary alcohol set the stage for the Pauson–Khand cyclization. Following the Brummond protocol, 1 was cyclized to 2. Methyl magnesium bro­mide was added, again to the more open face of the ketone, to give a new tertiary alco­hol. Exposure to stoichiometric OsO4 converted the more available alkene to the cis diol, that was protected as its cyclic carbonate 13. A central challenge in the total synthesis of the ingenanes is the construction of the “inside–outside” skeleton. This was achieved by the pinacol rearrangement of 13 with BF3•OEt2, to give 14. All that remained to complete the synthesis was selective oxidation. Allylic oxi­dation with stoichiometric SeO2 installed the secondary alcohol, that was acety­lated to give 15. The other secondary alcohol was then freed, and dehydrated with the Martin sulfurane, to give 16. A last allylic oxidation completed the synthesis of ingenol 3.

Stereospecific isomerization of 2-(1-bromoalkyl)-1-sulfonylaziridines using magnesium bromide

2005 ◽  
Vol 46 (38) ◽  
pp. 6541-6544 ◽  
Author(s):  
Michinori Karikomi ◽  
Takeshi Takayama ◽  
Kazuo Haga ◽  
Kazuhisa Hiratani
Keyword(s):  
Magnesium Bromide
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