Catalytic Enantioselective Intermolecular Cycloaddition of 2-Diazo-3,6-diketoester-Derived Carbonyl Ylides with Alkynes and Styrenes Using Chiral Dirhodium(II) Carboxylates

Abstract

Dirhodium(II) tetrakis[ N-tetrachlorophthaloyl-( S)- tert-leucinate], Rh 2( S-TCPTTL) 4, is an exceptionally effective catalyst for enantioselective tandem carbonyl ylide formation-cycloaddition reactions of 2-diazo-3,6-diketoesters with arylacetylene, alkoxyacetylene, and styrene dipolarophiles, providing cycloadducts in good to high yields and with enantioselectivities of up to 99% ee as well as with perfect exo diastereoselectivity for styrenes.

Modern Organic Synthesis with α-Diazocarbonyl Compounds

“…For example, the diazo compound 221 gave rise to the adduct 222 in 79% yield and 90% ee. 685 686 More recently, Hashimoto has also studied the use of aldehydes, 687,688 styrenes and acetylenes, 689 and indoles 690 as dipolarophiles in conjunction with these catalysts.…”

Catalytic Asymmetric Synthesis of Cyclopentyl β‐Amino Esters by [3+2] Cycloaddition of Enecarbamates with Electrophilic Metalloenolcarbene Intermediates

“…Instead, as was also realized by the group of Davies, the phthalimide–amino acid ligated dirhodium catalysts produced 3 a in good to excellent yields and modest to high enantioselectivities (entries 2–6). Surprisingly, [Rh 2 ( S ‐TCPTTL) 4 ] ( 5 g ), the chlorinated analogue of [Rh 2 ( S ‐PTTL) 4 ] rather than its fluorinated analogue [Rh 2 ( S ‐TFPTTL) 4 ], proved to be the catalyst of choice, thus providing 3 a in 87 % yield and 89 % ee . Further optimization with 1 mol % [Rh 2 ( S ‐TCPTTL) 4 ] in various solvents gave the optimum 91 % yield and 91 % ee of 3 a in 1,2‐dichloroethene (DCE) at room temperature (entry 12).…”

Asymmetric Total Synthesis of (−)‐Englerin A through Catalytic Diastereo‐ and Enantioselective Carbonyl Ylide Cycloaddition

“…Patterned after our original work,16a we initially evaluated the reaction of α‐diazo‐β‐ketoester 12 with methyl vinyl ether ( 13 a ) (3 equiv) using 1 mol % of [Rh 2 ( S ‐TCPTTL) 4 ] ( 8 ). The reaction in α,α,α‐trifluorotoluene at room temperature proceeded smoothly to give a 62:38 mixture of cycloadducts 11 a and 17 a (Table 1, entry 1).…”