Selective Stille Coupling Reactions of 3-Chloro-5-halo(pseudohalo)-4H-1,2,6-thiadiazin-4-ones

Abstract

A series of 3-chloro-5-halo(pseudohalo)-4H-1,2,6-thiadiazin-4-ones (halo/pseudohalo = Br, I, OTf) are prepared from 3,5-dichloro-4H-1,2,6-thiadiazin-4-one (3) in good yields. Of these the triflate reacts with tributyltin arenes (Stille couplings) chemoselectively to give only the 5-aryl-3-chloro-4H-1,2,6-thiadiazin-4-ones in high yields. This allowed the preparation of a series of unsymmetrical biaryl thiadiazines and ultimately a series of oligomers. Furthermore, treatment of 3-chloro-5-iodo-4H-1,2,6-thiadiazin-4-one (10) with Bu(3)SnH and Pd(OAc)(2) gave the bithiadiazinone which can also be further arylated via the Stille reaction to give bisthien-2-yl and bis(N-methylpyrrol-2-yl) analogs.

3-Chloro-5-(4-dodecylthiophen-2-yl)-4H-1,2,6-thiadiazin-4-one

“…3-Chloro-5-trifluoromethanesulfonate-4H-1,2,6-thiadiazin-4-one 3 [8] and 2-trimethylstannyl-4-dodecylthiophene 5 were prepared according to literature procedures [11]. -2-yl)-4H-1,2,6-thiadiazin-4-one (6).…”

“…Both are useful precursors to several polycyclic 1,2,6-thiadiazine systems [4,5]. For several years now we have been developing the chemistry of both these heterocyclic scaffolds [2][3][4][5][6][7][8][9][10]. Scheme 1.…”

“…Recently, we described the chemoselective Stille reactions of 3-chloro-5-trifluoromethanesulfonate-4H-1,2,6-thiadiazin-4-one 3 which enabled the preparation of unsymmetrical biheteroaryl thiadiazinones and oligomers such as 5,5'-(thiophene-2,5-diyl)bis[3-(thiophen-2-yl)-4H-1,2,6thiadiazin-4-one] 4 (Scheme 2) [8]. This potentially useful pentamer for optoelectronic materials was unfortunately poorly soluble, as such; the synthesis of an analogue bearing alkyl chains was targeted.…”

5,5′-Thiobis(3-methoxy-4H-1,2,6-thiadiazin-4-one)

“…1,2,6-thiadiazines could act as isosters to other 6-membered hetarenes; therefore, the formation of a thioamide onto the thiadiazine could offer a new scaffold for the synthesis of biologically active 1,2,6-thiadiazines could act as isosters to other 6-membered hetarenes; therefore, the formation of a thioamide onto the thiadiazine could offer a new scaffold for the synthesis of biologically active molecules. Some related amide-containing thiadiazines have been prepared, such as thiadiazinone 5, which can exist in the tautomeric form 5 by the displacement of the C-5 chloride of dichlorothiadiazinone 4 with hydroxide [19] (Scheme 1). Moreover, an attempt to deprotect benzyloxy derivative 6 led to the benzyl group migration to the N-2 position, yielding amide 7 along with the deprotected thiadiazine 8 [20] (Scheme 1).…”

3,5-Bis(4-dodecylthiophen-2-yl)-4H-1,2,6-thiadiazin-4-one

“…Both are useful precursors to several polycyclic 1,2,6-thiadiazine systems [4,5]. For several years now we have been developing the chemistry of both these heterocyclic scaffolds [2][3][4][5][6][7][8][9][10].…”