Diethylborylierung und Sulfidierung von ω‐Lactamen

Abstract

Diethylborylation and Sulfidation of o-Lactams1'' Several reaction modes of o-lactams [CH2],C( = 0 ) N H [A (n = 3), B (4), C (5), D (6), E (?), F (ll)] with Et3B are,observed between 20 and 110°C. The EtzB lactims EtzBOC=NICHz], (1) having various degrees of association [(l a)x; 1 b; (1 d)Z (X-ray structure); le; (If),] are formed by elimination of 1 mol of ethane. The condensation products Et&OC[ = CH(CHz), -l]NC = N[CHz], [2b; 2c (X-ray structure)] result by elimination of 1.33 mol of ethane together with the lactim derivatives Et,BOB(Et)OC = N[CHz], (3b; 3c). Thermolysis ( > 125°C) of (ld)z, l e , and (If), leads to mixtures, in which the compounds 2d, e, f and 3d, e, f, resp., have been identified (NMR, MS). Differences of the thermal behaviour of 1 af (s-cisltrans conformers, cisltrans lactirns, association degree) are discusyd. -From 2b, c and Hacac the N-acylamidines 0 = C[CH,],NC = N[CH2], (4b, c) are obtained, which react with (9-BBN)zS to yield the monomeric 9-BBN-o-thiolactims CsH1,BSCN[~H2],, [5b; 5c (X-ray stru~+ure)]. The 1:tter react with MeOH to give the o-thiolactams [CHZ],C( =S)NH (6b, c) and g-MeO-g-BBN, from which the 2: 2 MeOH addition compound (7)z (X-ray structure) is obtained. Uber einige praparative Moglichkeiten zur Einfuhrung von Schwefel in organische Sauerstoff-Verbind~ngen[~-~] rnit dem (9-BBN)2S-Reagenz[5261 haben wir vor kurzem berichtet. Die O/S-Austauschreaktionen verlaufen glatt, lassen sich allerdingsausgenommen z.B. mit 9(10H)-A~ridinon[~.~] -nur rnit H-acidfreien Verbindungen durchfiihren. Auch die am N-Atom unsubstituierten Lactame konnen mit dem (9-BBN)*S-Reagenz wegen bevorzugter Bildung von 9-HS-9-BBNC6] und/oder H,S-Abspaltung nicht ergiebig in Thiolactame umgewandelt werden. Um das neue Reagenz ohne Protolyse der SB-Bindungen auch fur die Lactamsulfidierung verwenden zu konnen, haben wir die H Die Edukte A -F liefem Produkte vom Typ 1 -3; die Ringgr6Ben werden mit af entsprechend A -F angegeben. n = l : A n = 4 : D n=2:B n=5:E n=3:C n=9:F n 1 Et Et 2 3 \ r > + B, 2OoC 1b -2 6ooc 2b + 3b (az) -0.33 Et 2c + 3c (a3) -1.33 EtH I -I E t H L 2-(If), -1 EtH 4 5 6

A Convenient Synthesis of 2,2-Diallylated Nitrogen Heterocycles by Allylboration of Lactams

“…Attempts to stop the above allylboration reactions at the monoaddition stage were unsuccessful. [9,10] As a part of our ongoing research program on the reductive allylboration of nitrogen heterocycles [11,12] we have investigated the reactions of lactams with allylic boranes. It is known that: (i) reaction of RMgX with 5-8-membered lactams leads to the corresponding 1-methyl-1-aza-2-cyclenes A or to a mixture of A and 2,2-dialkylated (arylated) heterocycles B ( Figure 1); [5][6][7] (ii) the compound C 14 H 23 N of unknown structure has been isolated from the reaction of 2-piperidone with allylmagnesium bromide; [8] (iii) ω-lactams containing an N-H bond dealkylate (20-115°C) trialkylboranes R 3 B (R ϭ Et, iPr), to give RH and O-borylated lactims having various degree of association.…”