Phenols as Starting Materials for the Synthesis of Arylstannanes via S_RN1¹

Abstract

Phenols are converted into aryl diethyl phosphate esters (ArDEP), which on reaction with sodium trimethylstannide (1) or sodium triphenylstannide (2) in liquid ammonia afford arylstannanes by the S RN 1 mechanism. Thus, the photostimulated reaction of phenylDEP (3), (4-methoxyphenyl)DEP ( 4), (4-biphenyl)DEP ( 5), (1-naphthyl)DEP ( 6), (2-naphthyl)DEP ( 7), and 2-(34), 3-(32), and (4-pyridyl)DEP ( 35) with 1 leads to monostannylated product in fair to excellent yields (20-98%). Also, substrates containing two or three leaving groups react with 1 under irradiation, affording the corresponding di-or tristannylated aryl compounds. With tetraethyl m-phenylene bisphosphate (15), tetraethyl p-phenylene bisphosphate ( 21), (4-chlorophenyl)DEP ( 22), and 1,3,5-tris(diethylphospho)benzene ( 30), the di-or trisubstitution products 1,3-bis(trimethylstannyl)benzene ( 19) (79%), 1,4-bis(trimethylstannyl)benzene ( 23) (95 and 97%), and 1,3,5-tris(trimethylstannyl)benzene (31) (57%) are obtained, respectively. Also, the reaction of 6 and 7 with 2 leads to substitution products in quantitative yields, and the reaction of 21, 22, and (4-bromophenyl)DEP ( 24) with 2 affords 1,4-bis(triphenylstannyl)benzene (38) in high yields (70-100%). On the other hand, the results obtained in the photostimulated reaction of 24 and (4-iodophenyl)DEP ( 25) with 1, as well as in the reaction of 25 with 2, clearly indicate a fast HME reaction.

Atherton–Todd reaction: mechanism, scope and applications

“…Aryl dialkyl phosphate, easily prepared starting from phenol in an AT reaction, can also be transformed into arylstannane derivatives by a S RN 1 reaction by the photostimulation of trialkyl [ 86 ] or triarylstannyl [ 87 ] ion in liquid ammonia as shown in Scheme 29 . This example shows that the AT reaction was achieved with CCl 4 as a halogenating agent.…”

Poly(dialkylstannane) and poly(diarylstannane) homo- and random copolymers synthesized in liquid ammonia

“…Yet a polymerization could by initiated by radicals, as radical reactions of organostannanes in liquid ammonia are well known. [29][30][31][32][33][34] The polydispersity index of 2.2 (Table 2) is in the typical range for radical chain growth polymerizations. Since the intermediates formed in situ in the first step did not react with each other to yield polymers, the species which initiated polymerization, therefore, must have been generated upon addition of the second portion of Bu 2 SnCl 2 -perhaps by reaction with sodium, as not the entire quantity of sodium is required for the formation of the observed stannides generated in the first step.…”

“…For reference purposes the corresponding homopolymers have also been included (Scheme 2). Conveniently, reactions of this type have found attention in the literature for some time [16][17][18][19] with a focus to form tin-carbon bonds as well as tin-tin bonds, [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and have been investigated in more detail more recently. 36,37 Notably, delocalization of s-electrons in the backbone of polystannanes was found to be responsible for the characteristic yellow color and the absorption maxima around 390 nm for poly(dialkylstannane)s (s-delocalization).…”

Aromatic and Heteroaromatic Substitution by S RN 1 and S N 1 Reactions

“…Me 3 SnAr can also be synthesized by the photoinduced reaction of aryldiethylphosphate esters [42] or aryltrimethylammonium salts [43] with Me 3 Sn À ions in liquid ammonia, in excellent yields (85-100%). These routes allow for the synthesis of arylstannanes in very good yields from inexpensive and commercially available phenols and anilines, which are easily converted to the corresponding phosphate esters and ammonium salts, respectively.…”

“…These stannanes are used in homocoupling reactions in the presence of Cu(NO 3 ) 2 Á2.5H 2 O to prepare almost quantitatively the corresponding biaryls [45]. This anion gives substitution products in good yields (62-100%) with ArX (X ¼ Cl, Br, OP(O)(EtO) 2 ) in liquid ammonia [38,42]. Hence, the treatment of ArSnMe 3 with Na metal in liquid ammonia, obtained by a photoinduced S RN 1 reaction between ArCl and Me 3 Sn À ions, yields ArSnMe 2 À ions by a selective Sn-alkyl bond fragmentation.…”