31152-14-4Relevant academic research and scientific papers
Photochemical synthesis of highly functionalized cyclopropyl ketones
Wessig, Pablo,Muehling, Olaf
, p. 865 - 893 (2007/10/03)
A series of di- and trisubstituted cyclopropyl ketones 11 were prepared by irradiation of ketones 3 and 5, which bear a leaving group adjacent to the carbonyl C-atom. The required ketones 3 could be easily synthesized either by functionalization of ketones 1 with a hypervalent iodine reagent, 2, or by O-sulfonylation of α-hydroxy ketones 7. The nitrates 5 were obtained by treatment of the corresponding α-bromo ketones with AgNO3. The irradiation of 3 and 5 must be performed in the presence of an acid scavenger (1-methyl-1H-imidazole) to obtain the cyclopropanes 11 in good yields. The synthetic efficiency of the method was, among other things, demonstrated by the preparation of a highly strained bicyclo[2.1.0]pentane 11i in good yield. The mechanism of the photochemical cyclization was investigated by means of photokinetic measurements, as well as by quantum-chemical calculations. It was shown that the presence of the leaving group substantially influences all steps of the photochemical reaction cascade. The X-ray crystal structures of 11j and exo-11k were also determined.
A new photochemical route to cyclopropanes
Wessig, Pablo,Muehling, Olaf
, p. 1064 - 1065 (2007/10/03)
Especially highly substituted cyclopropanes can be produced with a new photochemical approach. Starting with aromatic ketones that bear a leaving group adjacent to the carbonyl carbon atom, photolysis leads to the formation of 1,3-diradicals, which efficiently cyclize to cyclopropanes (see scheme; Ms=MeSO2).
Stereoselective Acyl Transfer Reactions controlled by the Diphenylphosphinoyl Group: X-ray Structures of Stable Crystalline Silylated Tetrahedral Intermediates
Feeder, Neil,Hutton, Gordon,Warren, Stuart
, p. 5911 - 5914 (2007/10/02)
Acyl transfer with LDA on benzoates of single diastereoisomers of 3-hydroxyalkyldiphenylphosphine oxides in the presence of trimethylsilyl chloride gives silylated tetrahedral intermediates in carbonyl displacement reactions with the stereochemically cont
OPENING OF THE CYCLOPROPANE RING IN α-BROMOCYCLOPROPYL KETONES BY THE ACTION OF TRIPHENYLPHOSPHINE
Kulinkovich, O. G.,Tischenko, I. G.,Sviridov, S. V.
, p. 885 - 888 (2007/10/02)
The reaction of a series of α-bromocyclopropyl ketones substituted in the three-membered ring with triphenylphosphine in alcohols in the presence of catalytic amounts of hydrochloric acid leads to the formation of the products from opening of the cyclopropane ring.Under analogous conditions 1-benzoyl-1-bromocyclopropane undergoes reductive dehalogenation.In boiling methanol 7-exo-benzobicycloheptane is converted into trans-1-bromo-2-benzoylmethylcyclohexane by the action of a mixture of triphenylphosphine and 1-benzoyl-1-bromocyclopropane and also by a mixture of triphenylphosphine and carbon tetrabromide.
COMPETITION OF REDUCTIVE DEHALOGENATION, ABSTRACTION-ADDITION, AND FAVORSKII REARRANGEMENT IN THE REACTION OF α-BROMOCYCLOPROPYL KETONES WITH SODIUM ALCOHOLATES
Kulinkovich, O. G.,Tishchenko, I. G.,Sviridov, S. V.
, p. 1275 - 1280 (2007/10/02)
Oxidation of the corresponding α-bromocyclopropylcarbinols gave 7-exo-bromo-7-endo-benzoylbicycloheptane, E-1-bromo-1-benzoyl-2-phenylcyclopropane, E-1-bromo-1-benzoyl-2-butylcyclopropane, E-1-bromo-1-acetyl-2-phenylcyclopropane, and 7-exo-bromo-7-endo-acetylbicycloheptane and the reactions of these compounds with sodium alcoholates were studied.Depending on the structure of the starting α-bromocyclopropyl ketone, the alcoholate used, and the solvent, the predominant reaction is reductive dehalogenation, Favorskii rearrangement or abstraction-addition.In the latter case, 2-alkoxycyclopropyl ketone intermediates are isomerized to 4,5-dihydrofuran derivatives.
