Large ring synthesis

The Ruzicka Cyclization (or Ruzicka Large Ring Synthesis) is a similar reaction in which cyclic ketones are formed from salts (Ca or Ba for smaller rings and Th or Ce for larger rings) of diacids ... 

F.i.a. Soft Nucleophiles. As mentioned before, dialkyl malonate enolates are useful terminators for cascade carbopalladations, leading eventually to rr-allylpalladium intermediates. This has been demonstrated by Ma and Negishi in their studies regarding allenes as relays for medium- to large-ring synthesis (Scheme... 

Robinson Annulation Robinson-Schopf Reaction Rosenmund Reduction Rosenmund-von Braun Synthesis Rothemund Reaction Rubottom Oxidation Ruff-Fenton Degradation Rupe Rearrangement Ruzicka Large Ring Synthesis Sabatier-Senderens Reduction Sachs (see Ehrlich-Sachs Reaction)... 

H. Kwart, K. King in The Chemistry of Carboxylic Acids and Esters, J. Patai, Ed. (Interscience, London, 1969) p 362 K. D. Bode, Houben-Weyl 7/2,640 (1973). Cf Ruzicka Large Ring Synthesis. 

Dianions also feature in both a small-ring and a large-ring synthesis. In the first, the dilithiated azetidinone (44) reacts with electrophiles to provide the substituted azetidinones (45) which can be elaborated further to thienamycin [E = MeCH(OH)]. In the second, the macrocycle yaralenone is readily obtained from the ring-closure products of the dianions (46) and (47) the... 

The potential for a,(o -bisdiazo-ketones in large-ring synthesis is well illustrated this year with a synthesis of the enedione (222) ° by treatment of (221) with [Cu(acac)2] in dry benzene at 60 °C. 

This reaction is used in the synthesis of large-ring compounds. 

In general, the methods of synthesis and reactions of oxiranes and thiiranes fused to ordinary or large rings are not particularly affected by the ring fusion. The reader is referred to Chapters 5.05 and 5.06, and reviews cited there, many of which include fused-ring examples. 

Synthesis of large ring alkanes and lactones from smaHer ring ketones via peroxides... 

An interesting footnote to the general synthesis of macrocyclic crown ether-type esters is found in the work of Ors and Srinivasan . These workers used cinnamate esters and diesters as precursors to large ring lactones. Depending on orientation, either truxil-... 

A spectacular application of the acyloin ester condensation was the preparation of catenaries like 11. These were prepared by a statistical synthesis which means that an acyloin reaction of the diester 10 has been carried out in the presence of an excess of a large ring compound such as 9, with the hope that some diester molecules would be threaded through a ring, and would then undergo ring closure to give the catena compound ... 

As d new utility of nitnle oxide in organic synthesis, synthesis of medium and large rings by intramolecular nimle oxide dimerization is reported fEq 8 67 ... 

---