Ring lactams

This polymer may be prepared by stirring the molten w-aminoundecanoic acid at about 220°C. The reaction may be followed by measurements of the electrical conductivity of the melt and the intrinsic viscosity of solutions in w-cresol. During condensation 0.4-0.6% of a 12-membered ring lactam may be formed by intramolecular condensation but this is not normally removed since its presence has little effect on the properties of the polymer. 

Nubbemeyer U (2001) Synthesis of Medium-Sized Ring Lactams. 216 125-196 Nummelin S, Skrifvars M, Rissanen K (2000) Polyester and Ester Functionalized Dendrimers. 210 1-67... 

Keywords Medium-sized ring lactams. Macrocyclization. Ring expansion. Rearrangement, Fragmentation... 

The pentacyclic core 15 of more complicated manzamines was built up by a final ring closure of the thirteen-membered ring lactam in 50% yield. The tetracyclic system and the alkyne unit of the reactant 13 supposed a pre-orientation, an intermediately formed activated pentafluorophenyl ester 14 led to the desired... 

Polymer bound HOBt as a catalyst was used in the synthesis of seven (23 % yield), nine (13%) eleven (5%) and thirteen-membered ring lactams (34%) [13c]. 

An auxiliary controlled enantioselective route to generate seven-membered ring lactams 75 used the a-alkylation of cyclic hydrazide derivatives 74. Initially, 6-chloro hydrazides 73,bearing the chiral information in the M-amino-pyrrolidine function underwent amidocyclization in the presence of a base. A subse-... 

A systematic investigation of the ring-closing metathesis of 138 in the synthesis of a range of fourteen-membered ring lactams 139 and lactones has been reported by Weiler. The geometry of the resulting double bond was determined, the position of the olefin was broadly varied. The ratios obtained were compared to that derived from molecular mechanics calculations, Eq. (15), Table 4 [34]. 

The use of cycloadditions for synthesizing medium-sized ring lactams is more or less restricted to the generation of seven-membered rings. The simplest method to generate azepinones seems to be the [6-1-1] reaction of a 1,6-dicar-boxylic acid chloride 148/152 and a phosphinimine 149, the in situ formed chloro enamine 150 underwent a Chapman rearrangement to give a cyclic imide 151/153 (Scheme 28)] [36]. 

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