Asymmetric intramolecular C–H insertion of sulfonyldiazoacetates catalyzed by Rh(II)

Substrate and Catalyst Effects in the Enantioselective Copper‐Catalysed C–H Insertion Reactions of α‐Diazo‐β‐oxo Sulfones

“…The major insertion product obtained differed with the use of copper or rhodium catalysts. The use of copper led to the formation of cis thiopyran 3 as the major insertion product (70–90 %) with minor amounts of trans thiopyran 4 (4–19 %) and trans sulfolane 5 (3–13 %) detected in the crude 1 H NMR spectra as well as minor amounts of byproducts, while, use of Rh 2 (OAc) 4 led to the formation of trans thiopyran 4 as the major C–H insertion product; Novikov also reported trans selectivity with rhodium catalysts . For this reason Cu(OTf) 2 was used in order to obtain racemic samples of the cis thiopyrans 3 .…”

Intramolecular Carbene C-H Insertion Reactions of 2-Diazo-2-sulfamoylacetamides

“…To further examine aliphatic C-H insertion of 2-diazo-2-sulfamoylacetamides, both 2-diazo-2-( N -benzyl- N -butylsulfamoyl)- N -methyl- N -phenylacetamide ( 1c ) and 2-diazo-2-( N -benzyl- N -butylsulfamoyl)- N , N -diphenylacetamide ( 1d ) were conducted under the optimal reaction conditions, affording 3-( N -benzyl- N -butylsulfamoyl)-1-methylindolin-2-one ( 3c ) and 3-( N -benzyl- N -butylsulfamoyl)-1-phenylindolin-2-one ( 3d ) chemospecifically in 76% and 85% yields, respectively (Table 2, entries 2 and 3). Similar to acyl diazomethanesulfonamides [24,25], aliphatic 1,4-, 1,5-, and 1,6-C-H insertions in the butyl group; aromatic 1,6-C-H insertion; Buchner reaction; and cyclopropanation on the benzene ring in the benzyl group did not occur, although diazosulfones and diazosulfonates favored aliphatic insertions [26,27,28,29,30,31,32].…”

Dirhodium Carboxylate Catalysts from 2‐Fenchyloxy or 2‐Menthyloxy Arylacetic Acids: Enantioselective C−H Insertion, Aromatic Addition and Oxonium Ylide Formation/Rearrangement

“…While intramolecular C−H insertion of α‐diazocarbonyl compounds generally leads to the formation of 5‐membered heterocycles and carbocycles, [25] Du Bois noted that when a sulfone group is incorporated into the cyclized product, six‐membered rings are formed due to the conformational impact of the sulfonyl moiety in the transition state [26] . Rhodium and iron catalysts have been utilized in the synthesis of sulfur containing 6‐membered heterocycles from α‐diazocarbonyl compounds, [24,27] however, high levels of enantioselectivity were not achieved [28] . In 2010, we described the use of copper‐bis(oxazoline) catalysts which led to the formation of cis‐tetrahydrothiopyran dioxides in up to 98 % ee [29] .…”

“… [26] Rhodium and iron catalysts have been utilized in the synthesis of sulfur containing 6‐membered heterocycles from α‐diazocarbonyl compounds,[ 24 , 27 ] however, high levels of enantioselectivity were not achieved. [28] In 2010, we described the use of copper‐bis(oxazoline) catalysts which led to the formation of cis‐tetrahydrothiopyran dioxides in up to 98 % ee. [29] In contrast, to date, rhodium catalysts have afforded the trans‐tetrahydrothiopyran dioxide diastereoisomer from α‐diazo‐α‐sulfonyl esters, with poor enantioselectivity.…”

“…[29] In contrast, to date, rhodium catalysts have afforded the trans‐tetrahydrothiopyran dioxide diastereoisomer from α‐diazo‐α‐sulfonyl esters, with poor enantioselectivity. [28] Our aim was to induce high levels of stereocontrol in the synthesis of trans‐tetrahydrothiopyran dioxides for the first time using α‐diazo‐β‐oxosulfones.…”