ChemInform Abstract: SILAFUNCTIONAL COMPOUNDS IN ORGANIC SYNTHESIS. 27. (ISOPROPOXYDIMETHYLSILYL)METHYL GRIGNARD REAGENT: A NEW NUCLEOPHILIC HYDROXYMETHYLATING AGENT FOR ALDEHYDES AND KETONES

1985 ◽  
Vol 16 (4) ◽  
Author(s):  
K. TAMAO ◽  
N. ISHIDA
Author(s):  
Douglass F. Taber

Carlo Siciliano and Angelo Liguori of the Università della Calabria showed (J. Org. Chem. 2012, 77, 10575) that an amino acid 1 could be both protected and activated with Fmoc-Cl, so subsequent exposure to diazomethane delivered the Fmoc-protected diazo ketone 2. Pei-Qiang Huang of Xiamen University activated (Angew. Chem. Int. Ed. 2012, 51, 8314) a secondary amide 3 with triflic anhydride, then added an alkyl Grignard reagent with CeCl3 to give an intermediate that was reduced to the amine 4. John C. Walton of the University of St. Andrews found (J. Am. Chem. Soc. 2012, 134, 13580) that under irradiation, titania could effect the decarboxylation of an acid 5 to give the dimer 6. Jin Kun Cha of Wayne State University demonstrated (Angew. Chem. Int. Ed. 2012, 51, 9517) that a zinc homoenolate derived from 7 could be transmetalated, then coupled with an electrophile to give the alkylated product 8. The Ramberg-Bäcklund reaction is an underdeveloped method for the construction of alkenes. Adrian L. Schwan of the University of Guelph showed (J. Org. Chem. 2012, 77, 10978) that 10 is a particularly effective brominating agent for this transformation. Daniel J. Weix of the University of Rochester coupled (J. Org. Chem. 2012, 77, 9989) the bromide 12 with the allylic carbonate 13 to give 14. The Julia-Kocienski coupling, illustrated by the addition of the anion of 16 to the aldehyde 15, has become a workhorse of organic synthesis. In general, this reaction is E selective. Jirí Pospísil of the University Catholique de Louvain demonstrated (J. Org. Chem. 2012, 77, 6358) that inclusion of a K+-sequestering agent switched the selectivity to Z. Yoichiro Kuninobu, now at the University of Tokyo, and Kazuhiko Takai of Okayama University constructed (Org. Lett. 2012, 14, 6116) the tetrasubstituted alkene 20 with high geometric control by the Re-catalyzed addition of 19 to the alkyne 18. André B. Charette of the Université de Montréal converted (Org. Lett. 2012, 14, 5464) the allylic halide 21 to the alkyne 22 by displacement with iodoform followed by elimination. In an elegant extension of his studies with alkyl tosylhydrazones, Jianbo Wang of Peking University added (J. Am. Chem. Soc. 2012, 134, 5742) an alkyne 24 to 23 to give 25.


Author(s):  
Alan R. Katritzky ◽  
Michael J. Cook ◽  
S. Bruce Brown ◽  
Raymundo Cruz ◽  
George H. Millet ◽  
...  

Synthesis ◽  
2009 ◽  
Vol 2009 (16) ◽  
pp. 2818-2824 ◽  
Author(s):  
Antonio Togni ◽  
Ján Cvengroš ◽  
Daniel Stolz

1989 ◽  
Vol 67 (1) ◽  
pp. 160-164 ◽  
Author(s):  
Edward Piers ◽  
Veranja Karunaratne

Transformation of the readily available keto acetal 14 into the enone 23 was accomplished via a seven-step sequence of reactions. Reaction of 23 with the bifunctional Grignard reagent 5 in the presence of copper(I) bromide – dimethyl sulfide, followed by intramolecular alkylation of the resultant chloro ketone 24, gave the tetracyclic ketone 25. Treatment of 25 with hydrogen in the presence of platinum afforded a mixture of the ketones 27 and 28 (42:58, respectively), which was transformed into a separable mixture of (±)-pentalenene (1) (32%) and (±)-9-epi-pentalenene (30) (33%). Keywords: ±-pentalenene synthesis, ±-9-epi-pentalenene synthesis, sesquiterpenoid synthesis, methylenecyclopentane annulation, bifunctional reagents, triquinane synthesis.


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