Rhodium‐Catalyzed Linear Cross‐Trimerization of Two Different Alkynes with an Alkene and Two Different Alkenes with an Alkyne

Abstract

Crossing paths with rhodium: A cationic Rh(I)/H(8)-BINAP complex has been found to catalyze the linear cross-trimerization of terminal alkynes, acetylenedicarboxylates, and acrylamides to give substituted trienes. The asymmetric linear cross-trimerization, giving substituted chiral dienes, has also been achieved by using monosubstituted alkenes and (R)-BINAP instead of terminal alkynes and H(8)-BINAP (see scheme; H(8)-BINAP = 2,2'-bis(diphenylphosphino)-5,5',6,6',7,7',8,8'-octahydro-1,1'-binaphthyl; BINAP = 2,2'-bis(diphenylphosphino)-1,1'-binaphthyl]).

Rhodium‐Catalyzed [3+2+2] and [2+2+2] Cycloadditions of Two Alkynes with Cyclopropylideneacetamides

“…Our research group recently reported the cationic rhodium(I)‐complex‐catalyzed linear cross‐trimerization of terminal alkynes, acetylenedicarboxylates, and acrylamides leading to substituted trienes, presumably through β‐hydrogen elimination from rhodacycle intermediates 12. We anticipated that the use of cyclopropylideneacetamides in place of acrylamides would afford either [3+2+2] or [2+2+2] cycloaddition products as a result of the absence of a β‐hydrogen atom.…”

Highly Chemo‐, Regio‐, and Enantioselective Rhodium‐Catalyzed Cross‐Cyclotrimerization of Two Different Alkynes with Alkenes

“…Recently, our research group reported the chemo-and regioselective synthesis of substituted trienes by the rhodiumcatalyzed intermolecular linear cross-trimerization of terminal alkynes, acetylenedicarboxylates, and acrylamides. [11,12] For example, a CH 2 Cl 2 solution of N-methyl-N-phenylacrylamide (3 a), di-tert-butyl acetylenedicarboxylate (2 a), and nhexylacetylene (1 a) or cyclohexylacetylene (1 b) were sequentially added to a CH 2 Cl 2 solution of the cationic rhodium(I)/H 8 -binap catalyst at room temperature to give either the linear trimerization product 4 aaa or 4 baa in good yield (Scheme 1). [11] However, tert-butyl acetylene (1 c) failed to react with 2 a and 3 a (Scheme 1).…”

“…[11,12] For example, a CH 2 Cl 2 solution of N-methyl-N-phenylacrylamide (3 a), di-tert-butyl acetylenedicarboxylate (2 a), and nhexylacetylene (1 a) or cyclohexylacetylene (1 b) were sequentially added to a CH 2 Cl 2 solution of the cationic rhodium(I)/H 8 -binap catalyst at room temperature to give either the linear trimerization product 4 aaa or 4 baa in good yield (Scheme 1). [11] However, tert-butyl acetylene (1 c) failed to react with 2 a and 3 a (Scheme 1). Surprisingly, trimethylsilylacetylene (1 d) reacted with 2 a and 3 a to give cyclotrimerization product 5 daa in a good yield with an excellent ee value, along with the linear trimerization product 4 daa (Scheme 1).…”

Highly Chemo‐, Regio‐, and Enantioselective Rhodium‐Catalyzed Cross‐Cyclotrimerization of Two Different Alkynes with Alkenes

“…[11,12] For example, a CH 2 Cl 2 solution of N-methyl-N-phenylacrylamide (3 a), di-tert-butyl acetylenedicarboxylate (2 a), and nhexylacetylene (1 a) or cyclohexylacetylene (1 b) were sequentially added to a CH 2 Cl 2 solution of the cationic rhodium(I)/H 8 -binap catalyst at room temperature to give either the linear trimerization product 4 aaa or 4 baa in good yield (Scheme 1). [11,12] For example, a CH 2 Cl 2 solution of N-methyl-N-phenylacrylamide (3 a), di-tert-butyl acetylenedicarboxylate (2 a), and nhexylacetylene (1 a) or cyclohexylacetylene (1 b) were sequentially added to a CH 2 Cl 2 solution of the cationic rhodium(I)/H 8 -binap catalyst at room temperature to give either the linear trimerization product 4 aaa or 4 baa in good yield (Scheme 1).…”