Efficient Synthesis of Cyclopropane‐Fused Heterocycles with Bromoethylsulfonium Salt

One‐Pot Synthesis of Cyclopropanes from Methylene Azabicyclo[3.1.0]hexanes Obtained by Formal Sequential [1+2]‐ and [2+3]‐Cycloaddition Reaction of Prop‐2‐ynylsulfonium Salts and Tosylaminomethyl Enones

“…Molecules such as amitifadine, alatrofloxacin, victrelis and procymidone are typical examples with significant biological activity (Figure ) . Although numerous methods for the synthesis of azabicyclo[3.1.0]hexane scaffolds have been developed, a general strategy with readily accessible starting materials, mild reaction conditions and excellent functional group compatibility has been elusive.…”

Recent Developments in Vinylsulfonium and Vinylsulfoxonium Salt Chemistry

“…Aggarwal and colleagues reported an efficient and versatile method for the formation of bicyclic cyclopropane-fused heterocycles 113 by subjecting β , γ -unsaturated amine derivatives 112 to reaction with diphenylvinylsulfonium triflate 1 , generated in situ from the precursor (2-bromoethyl)diphenylsulfonium triflate 3 [ 55 ]. Allylic amine derivatives 112 bearing Michael acceptors with various electron-withdrawing groups were successfully converted to the desired bicyclic 3-azabicyclo[3.1.0]hexanes 113 in moderate to good yields and with moderate to excellent diastereoselectivity ( Scheme 37 ).…”

“…This methodology was further explored by using chiral aza-Morita–Baylis–Hillman adducts 114 as reactants [ 55 ]. The annulation reaction with in situ generated diphenylvinylsulfonium triflate 1 gave the desired products 115 in moderate to good yields, and with excellent diastereoselectivity ( Scheme 38 ).…”

“…While the reaction of aza-Morita–Baylis–Hillman adducts 114 possessing an ester group as electron withdrawing group worked very well, unsaturated ketone 114a was less effective, giving the product 115a in low yield, albeit with excellent diastereoselectivity. In this case, a competing epoxy-annulation reaction, resulting from 1,2-addition of the sulfur ylide intermediate onto the methyl ketone (6- exo -trig cyclization to give 116 ) dominated, instead of the desired 1,4-addition onto the Michael acceptor (6- endo -trig cyclization to give 115a ) ( Scheme 39 ) [ 55 ].…”

Synthesis of Cyclopropyl‐Substituted Furans by Brønsted Acid Promoted Cascade Reactions

“…[21] Thetether length between the alkene functionality and the electron-deficient enyne was varied to deliver cyclo-propanes fused to five-or six-membered rings.The formation of polycyclicp roducts incorporating oxygen or nitrogen was also shown to be possible and the synthetically relevant 3-oxaand 3-aza-bicyclo[n.1.0]alkane derivatives 7f-i were obtained in good yields.T hese products are particularly valuable because the bicyclo[n.1.0]alkane motif is present in several natural products and other bioactive compounds. [22] The reaction was also performed on substrates in which one of the carbonyl groups of the diketone was replaced with an alternative electron-withdrawing substituent. When the ketone was replaced with an ester,aphosphonate,orasulfone group,t he reaction afforded the corresponding cyclopropyl furans 7j-l with good to excellent yields.The ynenediones 6f and 6h underwent spontaneous partial cyclization to deliver the desired cyclopropyl furans 7f and 7h immediately after Knoevenagel condensation.…”