81036-91-1Relevant academic research and scientific papers
Synthesis of 3-substituted 2-cyclohexenones through umpoled functionalization
Lechuga-Eduardo, Harim,Zarza-Acu?a, Eduardo,Romero-Ortega, Moisés
, p. 3234 - 3237 (2017/07/27)
A new protocol to obtain 3-substituted 2-cyclohexenones, was developed by reversing the chemical reactivity of 2-cyclohexenone. One-pot synthesis of 3-substituted 2-cyclohexenones can be achieved by treatment of 3-phenylthiosilyl enol ether with a mixture of t-BuLi/HMPA that allows hydrogen-selective exchange in presence of reactive electrophiles such as aldehydes, ketones and alkyl halides. This affords the corresponding product in moderate overall yield, after silyl enol ether cleavage and concomitant thiophenol elimination initiated with TBAF.
PREPARATION AND REACTIVITY OF FUNCIONALIZED ALKENYL-ZINC, -COPPER, AND -CHROMIUM ORGANOMETALLICS
Knochel, Paul,Rao, C. Janakiram
, p. 29 - 48 (2007/10/02)
β-Halogeno-α,β-unsaturated carbonyl derivatives were converted to the corresponding zinc organometallics 2a under mild conditions in THF (Zn dust, 25-45 deg C, 1-4h).These funcionalized alkenylzinc iodides react with a variety of alkenyl and aromatic iodides affording the desired coupling products in 40-97percent yield.The addition of a THF solution of CuCN*2LiCl to 2a affords the corresponding organocopper derivatives 2b which rect with electophiles, such as alkynyl and allylic halides, nitro olefins, enones, and chlorotrimethylstannane providing polyfuncional unsaturated carbonyl compounds in 71-95percent yield.The insertion of chromium (II) chloride to β-iodo and to some β-(p-tosyl)enones in DMF furnishes new funcionalized chromium (III) organometallics 2c which react with aldehydes providing γ-hydroxy unsaturated carbonyl derivatives in 40-91percent yield.The synthetic scope and the limitations of this methodology are discussed. Key words: funcionalized organozinc halides, alkenylchromium(III) compounds, copper-zinc organometallics.
An improved method for the syntheses of β-substituted cyclohexenones
Huang,Zhou
, p. 2369 - 2376 (2007/10/02)
An improved method for the preparation of β-substituted cyclohexenones is reported. Conditions were defined to effectuate the key desulfonylation-deketalization step in a mild manner. Several cyclohexenones bearing acid and/or base sensitive β-substituents were prepared by the modified method in moderate to good yields.
NEW METHODS FOR β-CONJUGATE ADDITION AND β-HYDROXYALKYLATION OF ENONES
Kim, Sunggak,Lee, Phil Ho
, p. 5413 - 5416 (2007/10/02)
β-Conjugate addition and β-hydroxyalkylation of enones have been accomplished by the reaction of ylides, derivated from enones via phosphoniosilylation, with activated olefins and aldehydes in the presence of trimethylsilyl triflate in tetrahydrofuran at
Use of Protected β-Bromocyclopentenones and β-Bromocyclohexenones as β-Acylvinyl Anion Equivalents
Shih, Chuan,Swenton, John S.
, p. 2825 - 2832 (2007/10/02)
Ethylene glycol ketals of the 3-bromocyclohex-2-en-1-one as well as its 2-methyl, 2-n-propyl, and 5,5-dimethyl derivatives have been prepared, and their reactions with butyllithium were studied.The organolithium reagents derived from the above compounds react with a variety of electrophiles to afford after acid hydrolysis the corresponding 3-substituted cyclohexenones.Attempts to prepare the ethylene glycol ketal of 2-methyl-3-bromocyclopent-2-en-1-one gave a low yield of the bromoketal.However, dithioketals of 3-bromocyclopent-2-en-1-one and its 2-methyl derivativecould be prepared in good yield.The metalation chemistry of the dithioketals in both the five- and six-membered-ring series was examined.The functionalization chemistry of the resulting organolithium compounds afforded after dithioketal hydrolysis 3-functionalized cyclohex-2-en-1-ones and cyclopent-2-en-1-ones.Several limitations of the chemistry using allyl bromide and cyclohexenone as electrophiles are noted.
An Efficient and Simple β-Acylvinyl Anion Equivalent for Cyclohexenones
Shih, Chuan,Swenton, John S.
, p. 4217 - 4220 (2007/10/02)
Dilithio species available from treatment of Δ3,4-3-bromocyclohexenone ketals with two equivalents of n-butyllithium serve as one-pot equivalents of β-vinyl-carbanions of cyclohexenones.These former ketals are available in good yield from the corresponding β-bromocyclohexenone by direct ketalization under controlled conditions.
