New and Efficient Synthesis of Stannyl Enamines

Abstract

a-and b-stannyl enamines have been synthesized in fairly to excellent yields starting from N-benzyl, N-tosyl ynamine and various organotin reagents under standard palladium catalysis.

N-Methyl-N-(2-phenylethenyl)trifluoromethanesulfonamide

“…Yield 59%, bp 92°C (0.5 mm). 1 The NMR spectra were recorded on a Bruker DPX 400 spectrometer at 400 ( 1 H), 100 ( 13 C), or 386 MHz ( 19 F); the chemical shifts are given relative to tetramethylsilane ( 1 H, 13 C) or CCl 3 F ( 19 F).…”

“…Hydrostannylation of N-tosyl-substituted ynamines TsN(Bzl)C≡CSiMe 3 [1] and TsN(Bzl)C≡CH [2] led to the corresponding N-tosyl enamines TsN(Bzl)C(SnBu 3 )=CHSiMe 3 [1] and TsN(Bzl)C(SnBu 3 )=CH 2 , and coupling of the latter with various organic halogen compounds RX afforded N-benzyl-N-(1-R-vinyl)-p-toluenesulfonamides TsN(Bzl)C(R)=CH 2 ; N-alkenylsultams were synthesized from N-alkynyl precursors [3]. Unsaturated derivatives of trifluoromethanesulfonamide containing a CF 3 SO 2 N(R)CH=CHR′ fragment were not reported so far.…”

Ynamides: A Modern Functional Group for the New Millennium

“…A complementary approach was developed by Cintrat77 through a palladium-catalyzed hydrostannation of ynamides, thereby gaining access to α-substituted enamides. The first attempt at the hydrostannation of silyl-protected ynamide 171 led to a mixture of ( E )- and ( Z )-enamides 172 (Scheme 49).…”

Palladium-Catalyzed Silastannation of Secondary Propargylic Alcohols and their Derivatives

“…10 In Pd(Ph 3 P) 4 -catalyzed silastannation of N-substituted aminoalkynes, the Si moiety adds to the a-position of the amino group with complete regioselectivity. 11 Concerning the reaction mechanism, Ito and Nakatsuji have performed a theoretical study, including the issue of regioselectivity, 12 which gives support to the generally ac-cepted catalytic cycle (Scheme 1). The catalytic cycle is believed to involve the following steps: (a) oxidative addition of R 3 SiSnR 3 to a coordinately unsaturated Pd species; (b) coordination of the alkyne; (c) insertion of the alkyne into the Pd-Sn bond; and (d) reductive elimination to afford the silastannated product and complete the catalytic cycle.…”