Pd-Catalyzed Enantioselective Hydroalkynylation of Cyclopropenes

Abstract

We report herein an easy, mild, and robust Pd-catalyzed enantioselective hydroalkynylation reaction of achiral cyclopropenes. Commercially available Pd(acac) 2 and ( R )-DM-BINAP proved to be the best combination to reach high diastereo- and enantioselectivities.

Cobalt‐Catalyzed Hydroalkynylation of Vinylaziridines

“…However, upon addition of Zn as reducing agent (50 mol%), enynes 3 at and 4 at were isolated even though in moderate overall yield (entry 20). The scope investigation highlighted the strong influence of the alkyne nature on the reactivity as previously reported in hydroalkynylation reactions [5h,8,10d,f,11,13b,24] …”

“…[12] Recently, efficient enantioselective versions were disclosed using gadolinium-and palladium-based catalysts. [13] In 2009, two independent studies on the hydroalkynylation of methylenecyclopropane derivatives were published. Sugimone found that a nickel(0)based catalytic system could perform addition of (triisopropylsilyl)acetylene without ring-opening of the cyclopropane moiety (Scheme 1b).…”

Synthetic Applications of Cyclopropene and Cyclopropenone: Recent Progress and Developments

“…The synthesis of chiral functionalized-cyclopropane derivatives by asymmetric functionalization of cyclopropenes was an efficient method. [16,33,47] Hou's team [47] found that chiral halfsandwich rare earth complexes were used in different asymmetric transformations. In 2017, the same group [48] reported an asymmetric carboamination reaction and annulation of cyclopropenes 85 with aminoalkenes 86 by chiral lanthanum catalysts La-1/ La-2 to provide 88 (1R,4S,5R,6S) and 89 (1R,4R,5R,6S) in good yield.…”

“…Synthesis of enantioenriched cyclopropane derivatives is a promising area of chemical research. [26] Therefore transitionmetal-catalyzed enantioselective carbozincation, [28,33] carbomagnesiation [15] and hydroacylation [34] reactions of diversely substituted cyclopropenes have been discovered successfully whereas asymmetric C(sp 3 )À H bond addition has remained unknown. In 2017 Hou's group [35] synthesized an enantioselective pyridylmethyl substituted cyclopropanes 52 by the CÀ H bond addition of 2-methylpyridines 50 to cyclopropenes 51 using a catalytic amount of TIPSÀ Y.…”

Cobalt‐Catalyzed Diastereo‐ and Enantioselective Hydroalkylation of Cyclopropenes with Cobalt Homoenolates

“…In the context of catalytic enantioselective functionalization of cyclopropenes (Scheme 1), Rh-catalyzed hydrostannation, [8] hydroboration, [9] hydroformylation, [10] and hydroacylation, [11] Cu-catalyzed hydroboration, [12] hydronitronylation, [13] carbocupration, [14] carbozincation, [15] carbomagnesiation [16] and hydroallylation, [17] Fe- [18] and Pd-catalyzed carbozincation, [19] hydroalkynylation [20] and lanthanide-catalyzed hydroamination, [21] hydroalkynylation, [22] and addition of 2methyl azaarenes, [23] Co-catalyzed hydroalkenylation [24] and hydrosilylation, [25] and NHC-catalyzed hydroacylation [26] have been reported for enantioselective synthesis of various functionalized cyclopropanes. However, few protocols have been developed for enantioselective introduction of diversified alkyl groups to cyclopropenes.…”