Direct formation of a tricyclic cycloheptanone-containing system by enolate condensation with a cyclopropanone derivative

Formation of Seven‐Membered Carbocycles by the Use of Cyclopropyl Silyl Ethers as Homoenols

“…3 The use of a cyclopropanol, which could be viewed as a “homoenol” or “homoenolate” equivalent, in the nucleophilic addition to a carbonyl compound or an acetal, has been limited primarily to 1‐alkoxy‐1‐siloxycyclopropanes 4. Little was known about the cognate homologous aldol or Mukaiyama reaction of parent cyclopropanols or siloxycyclopropanes 5. 6 We report herein an expedient entry to seven‐membered carbocycles by the Kulinkovich cyclopropanation of acetal‐tethered esters and a subsequent Lewis acid mediated ring expansion of the resulting cyclopropyl silyl ethers.…”

Access to C-15 Macrocyclic Ketones by Iterative Fragmentations of a Tricyclic System

“…Access to the targeted tricyclic fragmentation precursor was provided by the ready availability of the known dihydroxy ketone 1 , which was prepared in one pot from cyclohexanone and cyclopropanone (Scheme ) 5. Despite a reported yield of 67 %, it was only after modification of the experimental procedure that we were able to attain a reproducible yield of 44 % (see Experimental Section).…”

“…Tricyclic ketone 1 : Modified version of the procedure published in reference 5. Under mechanical stirring, a solution of MeMgBr in Et 2 O (!)…”

Access to C‐15 Macrocyclic Ketones by Iterative Fragmentations of a Tricyclic System

“…After 2 h, the almost clear reaction mixture was treated at 18±20 8C with saturated NH 4 Cl solution (180 mL). [5] Generally, lactams are synthesized by intramolecular CÀN bond formation. Washing of the organic layers (H 2 O, then sat.…”

“…We herein report the first application of a new synthetic strategy in which the target compounds are obtained from an appropriately functionalized tricyclic system by two consecutive fragmentations. [5] Despite a reported yield of 67 %, it was only after modification of the experimental procedure that we were able to attain a reproducible yield of 44 % (see Experimental Section). [4] Access to the targeted tricyclic fragmentation precursor was provided by the ready availability of the known dihydroxy ketone 1, which was prepared in one pot from cyclohexanone and cyclopropanone (Scheme 1).…”