Ketones cyclopropanation

Intramolecular Friedel-Crafts acylations of olefins also give cycHc a,P-unsaturated cycHc ketones. Cyclopropane fused bicyclo[5.3.0]octenones, thus obtained, were used in the preparation of the marine sesquiterpenes, africanol [53823-07-7] and dactjlol [58542-75-9] (174). 

H3C-N02 + Keton) Cyclopropan l-Methyl-2-nitro-l-phenyl- E17b, 1237f. (2-CO0R - ... 

Cyclohexan-(spiro-2)-2H-l,3-benzoxazin - -3,6-dihydro-E14a/2, 737 (H2N —Ar — CH2-OH + Keton) Cyclopropan... 

CsHpO]- (CH3)3CC0 Phot, of di-t-butyl ketone/ Cyclopropane EPR/ 143 2.0008. 80Davl... 

The reaction of benzoyl chloride with (Me3Si)2 affords benzoyltrimethylsi-lane (878)[626,749,750]. Hexamethyldigermane behaves similarly. The siloxy-cyclopropane 879 forms the Pd homoenolate of a ketone and reacts with an acyl halide to form,880. The 1,4-diketone 881 is obtained by reductive elimination of 880 without undergoing elimination of /7-hydrogen[751]. 

W I 0 E Q U I S T Cyclopropane synthesis Tetracyanocyclopropane synthesis from bromomalonitnie and ketones... 

This protective group was used to direct the selective cyclopropanation of a variety of enones. Hydrolysis (HCl, MeOH, H2O, it, 94% yield) affords optically active cyclopropyl ketones. 

The addition of diazomethane to a,/l-unsaturated ketones, e.g., benzalace-tone and benzalacetophenone, results in A -pyrazolines (16) which decompose thermally to the conjugated ketones (17). Cyclopropane formation is not observed in this instance. 

Thus the unsaturated ketones carvone, eucarvone and 1-acetyl-cyclohexane formed the cyclopropyl ketones (6), (7) and (8) while benzalaceto-phenone (9) affords l-benzyl-2-pheny 1-cyclopropane as a mixture of as and irons isomers (10) and (H) 233,234... 

The -position of the cyclopropane ring was established by the observed negative circular dichroism curve (Ae — 2.03 in dioxane at 298 m/i) and consideration of the inverse octant rule for cyclopropyl ketones. ... 

Interestingly, the reaction of tricyclenone (100) with morpholine also led to the exo isomer of the saturated ketone (101), involving the cleavage of the cyclopropane ring. 

Epoxidation of aldehydes and ketones is the most profound utility of the Corey-Chaykovsky reaction. As noted in section 1.1.1, for an a,P-unsaturated carbonyl compound, 1 adds preferentially to the olefin to provide the cyclopropane derivative. On the other hand, the more reactive 2 generally undergoes the methylene transfer to the carbonyl, giving rise to the corresponding epoxide. For instance, treatment of P-ionone (26) with 2, derived from trimethylsulfonium chloride and NaOH in the presence of a phase-transfer catalyst Et4BnNCl, gave rise to vinyl epoxide 27 exclusively. ... 

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