Synthesis of Nitrogen-Substituted Methylenecyclopropanes by Strain-Driven Overman Rearrangement of Cyclopropenylmethyl Trichloroacetimidates

Abstract

. (2014). Synthesis of nitrogen-substituted methylenecyclopropanes by strain-driven overman rearrangement of cyclopropenylmethyl trichloroacetimidates. Journal of Organic Chemistry, 79 (17), 8462-8468. Synthesis of nitrogen-substituted methylenecyclopropanes by straindriven overman rearrangement of cyclopropenylmethyl trichloroacetimidates AbstractNitrogen-substituted methylenecyclopropanes have been prepared by a strain-driven Overman rearrangement of cyclopropenylmethyl trichloroacetimidates. The reaction proceeds at room temperature and without the need of a transition-metal catalyst. Furthermore, it has been shown that C-3-substituted cyclopropenylmethyl trichloroacetimidates undergo a hydrolytic ring-opening reaction to form allenylcarbinols. AbstractNitrogen-substituted methylenecyclopropanes have been prepared by a strain-driven

[3,3]‐Sigmatropic Rearrangement of Cyclopropenylcarbinyl Cyanates: Access to Alkylidene(aminocyclopropane) Derivatives

“…Sigmatropic rearrangements involving cyclopropenylcarbinol derivatives constitute an interesting entry to diversely substituted alkylidene cyclopropanes . In 2013, Hyland and co‐workers reported that the [3,3]‐sigmatropic rearrangement of trichloroacetimidates F , derived from (2‐methylcyclopropenyl)carbinols E , provided a stereoselective access to alkylidene [ N ‐(trichloroacetyl)aminocyclopropanes] G possessing an exocyclic olefin of E configuration (Scheme ) . Although this so‐called Overman rearrangement of trichloroacetimidates F proceeds under mild conditions owing to the relief of ring‐strain, the scope is restricted to substrates E substituted by an electron‐rich or ‐neutral (hetero)aromatic group.…”

“…Substitution at C3 on the cyclopropene ring by methyl groups was also not tolerated because of the instability of the corresponding trichloroacetimidates F . Furthermore, attempts to convert products G into ureas by reaction of the trichloroacetamide moiety with pyrrolidine did not proceed efficiently …”

“…[26][27][28] In 2013, Hyland and coworkers reportedt hat the [3,3]-sigmatropic rearrangemento f trichloroacetimidates F,d erived from (2-methylcyclopropenyl)carbinols E,p rovided as tereoselective access to alkylidene [N-(trichloroacetyl)aminocyclopropanes] G possessing an exocyclic olefin of E configuration (Scheme 2). [29] Although this so-called Overmanr earrangement of trichloroacetimidates F proceeds under mild conditions owing to the relief of ring-strain, the scope is restricted to substrates E substituted by an electronrich or -neutral (hetero)aromatic group. Substitution at C3 on the cyclopropene ring by methyl groups was also not tolerated because of the instability of the corresponding trichloroacetimidates F.F urthermore, attempts to convert products G into ureas by reactiono ft he trichloroacetamidem oiety with pyrrolidine did not proceed efficiently.…”

Synthesis of Functionalized Alkylidenecyclopropanes by Ireland–Claisen Rearrangement of Cyclopropenylcarbinyl Esters

“…8 Recently, Hyland et al disclosed the rearrangement of trichloroacetimidates derived from cyclopropenylcarbinols bearing an electron-rich or -neutral aromatic substituent (Scheme 1, eq 2). 9 The substrates involved in these rearrangements were derivatives of cyclopropenylcarbinols lacking substituents at C3, the presence of which may have a dramatic influence on the reactivity by either raising the activation barrier 10 or inducing competitive rearrangement pathways. 9 Herein, we report our investigations on the reactivity of glycolates or glycinates A, derived from secondary cyclopropenylcarbinols, in the Ireland−Claisen rearrangement 11 with the goal of synthesizing highly functionalized and diversely substituted alkylidenecyclopropanes B, incorporating an α-hydroxy or α-amino acid subunit (Scheme 1, eq 3).…”

Recent Advances of Cyclopropene Chemistry

“…在该反应中, 由于体系中生成的 Mg 盐可以跟酯基配位, 从而影响了反应的立体选择性, 而 通过加入稍过量的 1,4-dioxane 可以大大改善这种情况, 使体系的 dr 值提高至＞95∶5(图 50). 胺酯取代的环丙烯的张力作用发生 Overman 重排制备 了氮取代的亚甲基环丙烷化合物 [56] . 反应具有很好的 普适性, 而且可以方便的制备环丙烷基脲和草酰胺等衍 生物, 为 N-取代的亚甲基环丙烷的合成提供了简便的 新方法(图 60).…”