 Welcome to this lecture on Transition Metal Organometallics in Catalysis and Biology. Today, we are going to be discussing two important topics. First, we are going to be finishing off our discussion on Ray P synthesis, an important acetylene based chemistry, which was developed in early 1900s also, and then which even have relevance in today's context, and then we will go on to another important topic, which is metathesis reaction, which also had been a very interesting area of chemistry and had been recognized by the conformment of noble prize as recent as 2005. So, now continuing with our discussion on Ray P synthesis, we would like to talk about the type of reaction that we have covered in the Ray P synthesis. What we had seen that Ray P synthesis sort of engulfs four different types of reaction, all starting from a very simplest C2 feedstock, which is acetylene, and conversion of acetylene to different vinyl derivatives like vinyl alcohol, vinyl cyanide, vinyl chloride, these are just one step conversion of acetylene, and these type of reactions are called vinylization reaction. Then we had also seen the reactions of acetylene with aldehydes, where it is just alkyne adelation reaction, where it just acetylene CH just adds against the CO bond. We have also seen the reaction of acetylene with carbon monoxide and water, and these are hydrocarboxylation reactions, and all of these what we had seen that they produce functionalized acetylene aliphatic feedstocks, which are very important for various transformations in chemical industry. In the last lecture, we had talked about cyclo oligomerization reaction, particularly in terms of with regard to making aromatic compounds using Ray P. So, for example, the reactions of three acetylene fragments giving benzene is an interesting example of this conventional reaction, or proceeding further, we have also looked into the reaction of four cyclo tetramerization of acetylene giving cyclo octatetraene, and these are nothing but conventional Ray P. Now, in the past lecture, we have also looked at the formation of metallative Ray P, where two different kinds of alkynes are used in presence of a metal, and these are called metallative Ray P. Now, what one can see is that in this case, one type of alkyne is used, and in this case two types of alkynes are used. Now, when one develops the compounds further, for example, in cases where three different kinds of alkynes are used, then things become more complex, like lack of selectivity, about 38 cross homocoupled and cross coupled products are obtained. So, the things are becoming different when there are three different kinds of alkynes. As we go from here, we see that this expansion of Ray P chemistry with regard to formation of different kinds of aromatic compounds by combination of a single type of acetylene to two types of acetylene to what happens when three different types of acetylene have been used. Now, to tell that this Ray P chemistry is relevant, even today is this fact that in this century in 2001, this problem of three different acetylene has been to give a very selective product has been very nicely demonstrated in this particular paper of journal of chemical society 2001, 1, 23, 7, 9, 2, 5, 2, 7, 9, 2, 6. So, here the metallative Ray P with three different acetylenes to give highly selective product has been successfully demonstrated, and we are going to see how this is done. This has been done. One thing to note here that these reactions of three different acetylene has not been done together all at once, but has been done in a stepwise fashion, as we will see in the synthesis. The synthesis starts with C8H13, this is acetylene number one with another acetylene. This is C6H13 reacting with a titanium catalyst, a titanium propene catalyst. So, this is an interesting catalyst at minus 50 degree centigrade, where the titanium is in plus 2 state to give this cyclopentamethylated species H13 isopere 2. So, here that reacts with the third acetylene at minus 50 degree centigrade, and then the reaction is red to room temperature to give this aromatic six-membered ring CO2-T butyl C6H13, C6H13 Ti X3, where X3 equals OIPR2 is O2-12. So, this when treated with H plus or D plus metallates the ring giving the product C6H13D, and this happens in 57 percent yield. This when treated with iodine gives iodide derivative in 56 percent yield, and this when treated with Penzaldehyde gives C6H13 this bicyclic compound in 49 percent yield. So, the important message over here is that this difficulty in attending selectivity in rapid synthesis was overcome in this beautiful work published in Journal of American Chemical Society 2001 volume 123 7925 to 7926 communication paper, where the three acetylenes acetylene one, two, and the third one have been used sequentially to produce this aromatic ring, and good thing is that they have been produced in a highly selective fashion in very high yields. This is different from the earlier challenges that was involved associated with rapid synthesis with regard to trying three different alkynes to form these aromatic compounds, and a nice demonstration of these can be seen in this recent paper 2001 paper, where one can see that highly selective product was synthesized using metallative repeat using three different alkynes and all under metallative repeat conditions, and another thing to note is that this recent work was published as recently as in 2001, which is about 70 or 80 years earlier than when the rapid chemistry was really in vogue. So, what it says and points out is that indeed rapid chemistry is very much relevant even in today's context, and there are quite a big amount of interest that is still there in the development of rapid reaction, and some various acetylic studies have emerged from rapid chemistry. So, with these I would like to end our discussion on rapid synthesis and to give you a feel for different rapid products. Let me just summarize the various kinds of products that we had observed and seen from rapid reaction. We had seen formation of halides, formation of acetates, alcohols, acrylates, benzene, cyclooptetraene, even they can be converted to various kinds of polymers and also be converted to different pyridine derivatives. So, this gives a flare of how rich the rapid chemistry is in terms of different products it produces and in short this slide sort of summarizes different form of rapid product or it tells the strength of rapid chemistry in terms of producing so many different compounds from a very single starting source. So, this is why the rapid chemistry is so important and more on this can be seen in this chemical review, which I had given reference of if somebody wants to look up can study the same and find more facts about it. So, with these we are going to stop our discussion on rapid chemistry and we are going to be taking up another important topic which is olefin metathesis. Olefin metathesis is a very interesting reaction. This is an important reaction and considered as a milestone in the development of polymer chemistry. If you look at the in terms of development you know the metathesis polymerization sort of came slightly even though it originated around at the time of olefin polymerization, polyolefin synthesis. However, the recognition in terms of its impact to the society came much later about 50 or more odd years later and as 2005 when it was awarded the Nobel prize and this Nobel prize for metathesis reaction were awarded to three distinguished chemists, Professor J. L. Chauvin, Professor Robert H. Grubbs and Professor Richard R. Schrock for their development or for their contribution in metathesis reaction. Unlike the previous topic which we have covered, where the rapid chemistry has been a contribution from the industry more than the academic world, the metathesis reaction had evolved in the laboratories of academia as well as industry and probably much more in the academic world than in the industry with many contributing from the world of academia. Professor Robert Grubbs is from Caltech, Professor Richard Schrock is from MIT and Professor Chauvin is from France. So, we have here we see the three professors two from US and one from France being awarded recognized for their contribution in metathesis. One thing at this juncture I must note that even though these three professors were formally recognized for their contribution in metathesis, metathesis as a field evolved with lot of players and lot of interested minds contributing and working on it even though three of them were finally recognized for their contribution. The metathesis as mentioned had been a child of industry to begin with because there were lot of unexplained unusual observations that were seen in the chemical industry when it was first observed. So, what is important over here is that as I said that both olefin polymerization as well as olefin metathesis where of interest in mid 1900s, 1950s and 60s it is the olefin polymerization which was sort of cracked much earlier or people found or understood where understood much earlier simple coordination insertion polymerization than olefin metathesis. So, the much of the time in metathesis was lost in trying to understand the phenomenon of metathesis and that is why the field of olefin metathesis sort of was developed about 10 or 15 or 20 years later than the field of olefin polymerization. In my opinion had the earlier breakthrough in terms of understanding and mechanism than olefin metathesis even though both probably were of interest or were being explored at in the similar around the same time, but one just got the understood better and earlier than the other. So, with these I conclude today's lecture where we have looked into this leptisynthesis particularly with regard to the cyclo olegromerization of acetylins to produce aromatic compounds using metallative repi and what we had discussed in today's lecture is about the use of three different alkynes to form aromatic compounds with highly substituted aromatic compounds with high selectivity because the one of the challenges had of lepy had been ongoing from one type to two type or three types of different alkynes is that there was a drastic loss of selectivity with about 30 odd 30 over 30 odd homo and cross couple products being formed simultaneously formed in the process. So, we had seen that in a beautiful work as late as as early as 2001 about 50-60 years since the discovery of repi that this has been solved very elegantly using three different acetylins to produce selective aromatic products using a titanium catalyst we had covered that in this lecture and we have also looked into different kind of products that repi chemistry throws out and which shows that it makes a large amount of products which completes the whole cycle. So, the utility of repi chemistry still stands today and with that we have also completed our discussion on repi and we had initiated our discussion of olefin metathesis another very interesting Nobel Prize award winning reaction with regard to olefin method metathesis what we had spoken about is that even though olefin metathesis and olefin polymerization probably were of interest around the same time which is around mid 1950s 40s 60s it is the olefin polymerization which was understood much earlier and its repercussions fell and recognized much earlier with Nobel Prize in 1953 or 1963 whereas for olefin metathesis the puzzle remained for another two or three decades because before people could understand what is going on in this new and which diverse chemistry and then finally the impact of it was felt slightly a few days because later with the Nobel Prize being awarded in 2005 about 50 years after then that of olefin polymerization. So, metathesis also is an important breakthrough in the field of polymerization we would also look into various aspects of olefin metathesis have in the subsequent lectures what is important to say is that unlike repi chemistry which had been exclusively or had been solely developed in the purview of industry metathesis development had been largely a both in the academic as well as industrial world even though the three persons who have been recognized finally recognized and given awarded the Nobel Prize belong to this academic world two from US and other from France. So, with this I conclude today's lecture we are going to be taking discussing a lot on olefin metathesis when we take up the next lecture. So, I thank you once again for being with me in this exciting journey of different applications of transition metal organometallics in chemical catalysis and I look forward to being with you in the next lecture where we are going to be talking about olefin metathesis in much more detail and depth. Till then, goodbye and thank you.