[2,3]-Sigmatropic Rearrangement of Ynamides: Preparation of α-Amino Allenephosphonates

Abstract

α-Amino allenephosphonates were easily prepared in two steps from protected amines, propargyl alcohols, and chlorophosphites. First, ynamides were synthesized from unprotected 1-bromopropargyl alcohols using a copper(II) catalyzed coupling reaction. In the second step, the previously prepared ynamides were transformed directly to allenes through a [2,3]-sigmatropic rearrangement of propargyl phosphites. This efficient method led to the formation of a series of α-amino allenephosphonates with diverse substituents on the amine, the phosphonate, and the allene moieties.

Cerium(iv) ammonium nitrate mediated 5-endo-dig cyclization of α-amino allenylphosphonates to spirodienones

“…To explore the scope and limitations of this 5-endo-dig cyclization, a series of α-amino allenylphosphonates S1-S18 (see supporting information) was prepared 31 and converted to the corresponding spirodienone lactams 11-26 by treatment with the CAN in a mixture of acetonitrile and water (2:1) (Scheme 4). Although the reaction appeared to be general with possible modifications on the para-methoxybenzyl ring (compounds 23-24), the sulfonamide (both tosylamide and mesylamide are transformed into the spirodienone lactam eg.…”

Selective Reduction of Amino Allenephosphonates: Preparation of α‐Amino Vinylphosphonates

“…[23] 13 N-Benzyl-N-[1-(5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2-yl) N-Benzyl-N-[(1E)-1-(5,5-Dimethyl-2-oxido-1,3,2- N-Benzyl-N-[(1Z)-1-(5,5-dimethyl-2-oxido-1,3,2-dioxaphosphinan-2 All solvents and chemicals were purified based on standard procedures.…”

“…Z-α-Amino vinylphosphonates were prepared with good selectivities up to Ͼ 95:5. dialkylphosphites to ketene acetals (Scheme 1, path g) [19] or α-halo vinylamines (Scheme 1, path h) [20] represents a valuable alternative for the synthesis of α-AVPs. [23] Continuing our ongoing research into the synthesis of unsaturated phosphonates, in this paper, we report the chemoand stereoselective reduction of α-AAPs 3 to α-AVPs 4. Moreover, the synthesis of α-AVPs often requires the introduction of specific substituents that make the α-AVP products unstable.…”

“…[22] More recently, we reported a simple and efficient synthesis of αamino allenephosphonates 3 (α-AAPs) by the [2,3]-sigma-Selective Reduction of Amino Allenephosphonates tropic rearrangement of ynamido-alcohols (Scheme 2). [23] Continuing our ongoing research into the synthesis of unsaturated phosphonates, in this paper, we report the chemoand stereoselective reduction of α-AAPs 3 to α-AVPs 4. This approach represents a new alternative for the synthesis of α-AVPs, and uses simple reagents and simple experimental conditions to prepare highly functionalized substrates.…”

Regioselective Synthesis of Highly Substituted Imidazoles via the Sequential Reaction of Allenyl Sulfonamides and Amines

“…8,9 Various nitrogen-containing building blocks including nitrogen heterocycles were successfully synthesized from allenamides and ynamides. 10,11 Recently, Rabasso and co-workers 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 reported a simple and efficient synthesis of α-amino allenephosphonates by the [2,3]-sigmatropic rearrangement of ynamido-alcohols 12 and selective reduction of amino allenephosphonates for the preparation of α-amino vinylphosphonates. 13 These α-amino allenephosphonates represent a kind of allenes substituted with both an electron-withdrawing group and an electron-donating group, thus they would show some special reactivity.…”