Reaction of dienes with chlorosulfonyl isocyanate

Abstract

Chlorosulfonyl isocyanate (CSI) may play an antarafacial role as the 2 component in concerted reactions with T2a systems. It does so in additions at low temperature to such conjugated dienes as 1,3-butadiene, isoprene, 2,3-dimethyl-l,3-butadiene, the cis,irons-1,3-pentadiene mixture, and irons-1,3-and trans,trans-2,4hexadiene. The /3-lactam products are Markovnikov-oriented 1,2-cycloadducts in which CSI has added to the terminal double bond. In no instance was the symmetry-allowed T4S + T2a reaction observed. These initially formed N-chlorosulfonyl-^-lactams thermally rearrange to Nand 0-1,4 cycloadducts. Alternative stepwise and concerted mechanisms are proffered. Alkaline hydrolysis of the N-chlorosulfonyl-/3-lactams in acetonewater conventionally afford NH 2-azetidinones. In methanol, solvent participation in the alkaline hydrolysis led to ring cleavage and the formation of bis esters of /3-amino(A7-sulfonic acid)carboxylie acids. Since both hydrolytic processes probably commence by displacement of Clby OH-, the intermediate sulfonic acid must be trapped by the methanol as the sulfonate ester. In the nmr spectra of 2-azetidinones, four-bond coupling was

β-Lactam Derivatives as Enzyme Inhibitors: Carboxy Peptidyl Derivatives of (S)-4-Oxoazetidine-2-carboxylate as Peptidomimetics

“…The spectrum of 5a shows a coupling between N-H and 3-H trans J = 2.0 Hz, and between N-H and 3-H cis J = 1.1 Hz. This is in contrast to other β-lactams described in the literature, where the coupling with the cis-H shows the larger constant [5] . Another effect should be noticed.…”

“…Compounds 5 show a higher polarity, they are crystalline compounds with exact melting points. Their IR spectra are not significantly changed, but in their 1 H NMR spectra an additional long range coupling [5] , J = 1-3 Hz, of the protons at C-3 with the N-H is observed. The spectrum of 5a shows a coupling between N-H and 3-H trans J = 2.0 Hz, and between N-H and 3-H cis J = 1.1 Hz.…”

Synthesis of Assigned Structure of Cairomycin A, 6-Isopropyl-2,5-Diketopiperazine-3-Acetic Acid and Its Β-Lactam Analogue N`- (3-Methyl-1-Hydroxybutyr-2-Yl) Azetidin-2-One-4-Carboximide

“…Moriconi has suggested (Moriconi and Meyer, 1971) a mechanism for the cycloaddition reaction, in which he proposed that the reaction starts with π complex formation and proceeds through the polar transition state.…”

General Preparation of 1‐Substituted (E)‐1,3‐Dienes under Mild Conditions

“…1,3‐Dienes1 are chemical motifs of great interest as a result of their unique reactivity. They are building blocks for the preparation of diverse carbacycles2 and heterocycles,3 and derivatives of cyclopropanes4 and β‐lactams 5. Moreover, unsaturation of this type is often found in natural products of biological relevance, e.g., arachidonic acids,6 retinoids,7 antibiotics,8 or complex marine natural products 9.…”