Orthoamides and Iminium Salts LXXXII: Cleavage of Orthoamides of Alkynecarboxylic Acids by Elemental Iodine – A New Method for the Preparation of Vinylogous Guanidinium Salts

Abstract

Orthoamides of six alkynecarboxylic acids, possessing reactive substituents in 3-position, are transformed by elemental iodine to the corresponding vinylogous guanidinium iodides. The constitution of two of the iodides was established by crystalstructure analysis.

Crystal structure of 2-bromo-3-dimethylamino-N,N,N′,N′,4-pentamethyl-4-(trimethylsilyloxy)pent-2-eneamidinium bromide

“…For the synthesis of alkynyl orthoamides and propiolamidinium salts, see: Weingä rtner et al (2011). For the synthesis of vinylogous guanidinium iodides and bromides, see: Kantlehner et al (2012a). For the crystal structure of 3-phenyl-N,N,N 0 ,N 00 -tetramethyl-1-ethyne-1carboximidamidium bromide, see: Tiritiris & Kantlehner (2012b (Blessing, 1995) T min = 0.285, T max = 0.530 32287 measured reflections 5164 independent reflections 3394 reflections with I > 2(I) R int = 0.095…”

“…propiolamidinium triflates by reaction with triethylsilyl trifluoromethanesulfonate is well known in literature (Weingärtner et al, 2011). Alkyne orthoamides are transformed by elemental iodine or bromine to vinylogous guanidinium iodides or bromides (Kantlehner et al, 2012a). Phenyl substituted alkyne orthoamides like 3,3,3-Tris(dimethylamino)-1-phenyl-prop-1-yne (Weingärtner et al, 2011) behave differently, it reacts with bromine to give 3-Phenyl-N,N,N′,N′′-tetramethyl-1-ethyne-1-carboximidamidium bromide (Tiritiris & Kantlehner, 2012b).…”

3-Phenyl-N,N,N′,N′-tetramethyl-1-ethyne-1-carboximidamidium bromide

“…For the synthesis of alkynyl orthoamides and acetylenic amidinium salts, see: Weingä rtner et al (2011). For the synthesis of vinylogous guanidinium iodides and bromides, see: Kantlehner et al (2012). For the crystal structure of N,N,N 0 ,N 0 ,N 00 ,N 00 ,N 000 ,N 000 -octamethyl-(but-2-yne)-bis(amidinium)-bis(tetrafluoridoborate), see: Drandarov et al (2012).…”

“…They can be prepared by cleavage of alkyne orthoamides with triethylsilyltriflate or benzoyl chloride (Weingärtner et al, 2011). Various alkyne orthoamides are transformed by elemental iodine or bromine to vinylogous guanidinium iodides or bromides (Kantlehner et al, 2012). Phenyl substituted alkyne orthoamides like 3,3,3-tris(dimethylamino)-1-phenyl-prop-1-yne (Weingärtner et al, 2011) behave differently, it reacts with bromine to give the title compound.…”

Orthoamide und Iminiumsalze, LXXXII [1]. Die Spaltung von Alkincarbonsäure-orthoamiden mit Trimethylsilylazid / Orthoamides and Iminium Salts LXXXII [1]. The Cleavage of Orthoamides of Alkynecarboxylic Acids by Trimethylsilyl Azide

“…B. 3-Dimethylamino-2-iod-prop-2-en-amidinium-iodide aus den entsprechenden Orthoamiden und Iod zugänglich [14]. Aus Brom und 1,1,4-Tris(dimethylamino)phenylprop-2-in erhält man N,N,N ,N -Tetramethyl-phenylpropinamidiniumbromid [15].…”