hypervalent_iodine

You're talking about the cyclopropanation step (there are no epoxides in there). It's not actually a new discovery. The group that Williams was collaborating with (Davies group) used Rh2(S-DOSP)4 and Rh2(S-PTAD)4 to achieve the assymetric [4+3] addition (which then underwent a Cope rearrangement to for the 7 membered ring). This was based on previous work that found it worked as a chiral catalyst for the synthesis of tropanes in a similar fashion. Looking at the paper (I copied an excerpt below), the best yields and ee's were obtained using Rh2(S-PTAD)4 in conjunction with a combination of a methyl ester at R1 and OTBS at R2 on the vinyldiazoacetate, with the remaining to R groups unfunctionalised. This just changes the electrostatic and steric environment of the substrate, which in turn affects how the Rh catalyst approaches it and how the reactants come together in space to undergo the pericyclic reaction. The model shown in the paper (below) suggests that the Rh catalyst aligns with the vinylcarbenoid with the OTBS facing away from the phthalimido groups (for steric reasons). The diene then attacks from the front face in the [4+3] addition and the compound then undergoes the Cope rearrangement. Also, the reaction actually has quite a nice scope, in that it could be performed using a multitude of different dienes with good yields and ee's. The microwave step, from what I can tell and have read, induces a Claisen type rearrangement.

These are the pictures that I refer to in my above answers: (I unfortunately had no chem draw program handy at the time, so excuse the blurriness) I got these pictures by collaborating the results of a couple of papers (E.A. MacGregor et al., 2001, 1546, 1-20; T. Kuriki and T. Imanaka, 1999, 87, 557-565). The mechanism I drew I had to do a bit of problem solving to get too, since one paper gave 2 alternative routes and the other one was dealing with a modified substrate. Having dealt with sugar chemistry in the past, I am quite positive with the mechanism I have drawn but it is, of course, up for discussion.

Great post mississippi! I've always loved hydrazine I've never actually seen the synthesis of Viagra before, it's quite simple and eloquent when you look at it. I thought I'd include a synthesis that the group I work in helped complete before I started with them (found at http://www.organic-c...07December.shtm). The group I work in (Williams group) worked mostly on the Wittig reaction at the end of the synthesis, which is nice in itself since the ylide can have a wider application outside of this synthesis. Anyway, I like this because it's wonderfully entioselective and it scares first years to see what organic chemist's have to deal with. Overall reaction: First synthesis leading to (2) Second synthesis leading to (15) Final synthesis leading to (3) As Horza said, this is true but using cheap catalysts in your reactions are not always possible. Also, you are incorrect in saying 'theoretically to 100%'. You almost always have byproducts in your reaction, some that form reversibly some that don't. Quantitative yields are nice, but hard to get.

Ha, yeah, I realised that after I'd posted it and gone to bed. Oh wells.

acid base titrations are a fairly simple tool you can use to tell the molarity of a HCl solution. There are plenty of articles online that can walk you through it. Here are a few: http://en.wikipedia.org/wiki/Acid-base_titration

Read my above post again. I did tell you how to do it. What is this for?

Hmm, that's true. I wouldn't use BuLi anyway. I should think that it'll add to the sulphone as a nucleophile as opposed to acting as a base.

In this case, given the product the OP is after, I doubt it's a boc/fmoc, etc. group. I suspect it's a case of a magical, missing R group of nondescript nature.

I think you need to talk to your professor. For starters, you need to clear up the issue relating to the missing R group (it's almost definitely meant to be there). Secondly, I think you should ask him which enzyme you are inhibiting. I fail to see how you 'theoretically' work out what would work best without knowing what you need to make work. Or perhaps I'm misinterpreting the aim of this assignment. On that note, since this is an assignment, I don't think it's exactly fair that we tell you the answer straight up. That being said, Horza has pretty much given you your answer relating to the first step and you seem to be on the right track with that. What you should try and do is see if you can find what the pKa of the proton you're removing is - if you can't find the exact molecule on scifinder, try looking up very similar derivatives. In terms of the pKa, you could even just look up a simple methane sulphonamide to get an idea of what you'll need (though you are correct in that you'll need a strong base). If you can find that, you should be able to find a suitable base. With respect to the electrophile, you need to think why would you need the electrophile? What is it doing? As a hint, it relates to what happens when you react your sulphonamide with the phosphorous group and what subsequently happens to the leaving group (the Cl ion).

From memory, a lot of it has to do with phosphorylation and dephosphorylation of one of the proteins in your retina in response to light (or a lack there-of). I'm afraid it's been a while since I've done this, so I don't know much more than that without looking it up.

Or another Italian add for rental apartments in Rome.

Well, I know MoN won't need this anymore as they will have finished year 12, but I thought I might respond anyway. Judging by the fact that MoN mentioned EEI's, I can gather that he/she did his senior high school years in QLD, Australia, which just happens to be where I graduated from high school. So for the benefit of other students who are looking for some good EEI's to do, here is a list of the ones I did in Chemistry and Biology. I received no less than an A grade on all of these, so provided you put the work in and things haven't changed too much in 5 years, you should be on the right track: Chemistry Reaction kinetics and mechanisms using the Landolt clock reaction (aka iodine clock reaction). The concept behind this can be a littlle bit to get your head around when . This was quite a simple experiment, but there is a fair amount of maths involved in calculating all of the initial rates, etc. You only need very access to relatively simple and safe chemicals too, depending on what variation you use. I found an interactive version of the experiment that would be a great help in developing some sort of protocol: interactive clock reaction Also, if your teachers have access to the Journal of Chemical Education I know that there are a number of articles that list procedures as well as detailing other bits of very helpful information. The main thing with this as an assignment is to demonstrate a sound understanding of how to interpret and properly analyse kinetic data. From this experiment, you should be able to interpret initial rates, the reaction rate constant (k) and the order of your reactants/reaction. Biology The affect of light and sucrose on the growth and development of plants I'm not sure if this one is particularly useful to most high school student's the way that I did it, since my school was one of only a few that I know of with a dedicated plant tissue culture lab. In any case, the experiment that I was required to do involved investigating two parameters, light and sucrose availability, and how those changed the growth and development of plants. It's a simple enough thing to do if you have the proper labs, so a lot of the work comes from how in depth you scientifically justify your results. For instance, we found that plants growing with sucrose but without light still grew - in fact, they grew significantly taller than those that had light - but the had next to no leaf or root growth. Phenomena like that clearly need some in depth explaining to gain good marks. It is also worth while to try and analyse the quantitative data with proper statistical measures. If you wanted to go hard out with the stats analysis, you might do a Welch two-tailed t-test and an F-test. If you have a PTC lab, then presumably this is something you will be doing anyway and you will have a protocol for it. Alternatively, you could do a similar experiment growing plants in soil under abiotically controlled conditions as MoN suggested. I did one looking at soil salinity and a few other factors once that worked quite well as an assignment. Other than that you could possibly look at antibiotic resistance in bacteria such as E coli, if your school allows it.

Depends if you want the dihydrate or not. Anhydrous SnCl2 can be made using dry HCl gas and tin. The dihydrate just used aqueous HCl and tin followed by careful evaporation of residual water to yield your crystals. You can also add acetic anhydride to the dihydrate to make it anhydrous. Presumably if you're needing to make this you don't work in a lab, so firstly, what is this for? Secondly, this synthesis is somewhat dangerous and I would advise you to try and purchase SnCl2 if you can rather than making it yourself.

I myself don't do this sort of research, but the reaction is plausible if you ignore the missing R group. Did you have a particular question relating to this reaction or did you just want to know if people are doing it/if it has been done before? A good way to find out if this has been done previously is to do a search by molecule in scifinder (if you have access to it).

Vitamin C is ascorbic acid, but that is not the same as citric acid. Structurally and metabolically they are very different.

No where I would trust, I'm afraid.

TNT is the name of a company that makes fireworks. I suppose it is possible to make them with TNT, but I have no idea why you'd want to. And you would most certainly not want to use it as rocket fuel. You need to think about what you're suggesting before you go around telling people efficient ways of maiming/killing themselves.

We not only have the ability to metabolise it, we have to. So do plants. It forms a part of Kreb's cycle - aka the citric acid cycle - which is used for cellular respiration.

Oh my god, dragon. You did not just suggest someone try and use TNT. Scarily enough, this isn't the dumbest thing you've ever said. People don't use TNT in fireworks, for starters.

That would depend entirely upon what scholarship you're trying to get. Have a look through the university's web site and pick the scholarships best suited to you. The types of people and situations they are designed for will dictate how you should approach your application.

You do not need to study the intricacies of every religion in order to decide that you do not believe in a God/s. What you seem to be suggesting is that atheists should study every religion to see if the idea of one or another God/s appeals to them. What you are demanding is in fact a false belief. Belief in a God is quite a simple question, in reality. Do I believe in a God/s? No. Have a read any religious texts? Not past the first page of Genesis. Will reading all about the wonderful things that a God/s can do for me sway my belief and more importantly, should it? Most definitely not. I do not believe in a God/s because it/they has/have no evidentiary basis (for or against) - and you cannot claim bibles and other such texts to be evidence, because if that were the case then I should suggest you start believing in wolves that can blow your house down. Marat made the analogy of Bugs Bunny before, which I think stands quite true. I have not read every single loony tunes book or seen every looney tunes show/movie, yet I do not need too for me to know that Bugs Bunny isn't real. Why should people of religious faith be exempt from the rule that atheists supposedly have to abide by to become true atheists? By your standards, a person who is Catholic or Muslim, etc. and who hasn't studied every other religion to be sure that they are worshipping the correct deity should be guilty of just as much ignorance. The idea of God is merely a concoction designed by people a long time ago to understand phenomena that they did not have the tools or knowledge to properly and scientifically explain. The question of, 'why are we here?' is one that still plagues a lot of people. From the unknown comes fear and what better way to eliminate that fear than to create a metaphysical deity to give ultimate levels reassurance? The concept of religion is simply an arbitrary faction of our own making that has historically been used to capitalise on that fear. Tithes, anyone?

A few posts ago you said that you have a problem with people who do not give a second thought for tolerance or open mindedness. What then gives you the right to try and sell religion to people who either do not believe in a God/s or have alternative sets of beliefs? Is that not intolerant? Why does one of these religions have to be right? Finally, in the spirit of being open minded, may I ask whether or not you have looked into scientific reasonings behind theories such as evolution? Some people need to have faith in a higher power and some people do not. The former is certainly not a necessity, as you claim.

I agree with mississippi. The main issue is zealots from either side being disrespectful of the 'opposition' by trying to forcibly push their beliefs onto one another. As was mentioned, disagreements on intellectual matters are just that. Though it is a curiosity for me at least to understand why one would choose to believe in creationism, it is not for me to simply tell someone who did believe in ID, etc. that they are simply wrong and spend hours in a heated debate that will in reality get nowhere except for where we started. Can we coexist peacefully? Of course we can. Will we? On a larger scale, absolutely not. People are stubborn and unfortunately those who cause a lot of the troubles do so because they cannot simply live and let live. Some people just enjoy 'stirring the pot', consequences be damned. Having said that, I also believe that being disrespectful of another's beliefs doesn't necessarily dictate violence or maliciousness. I often feel that the people who go around to people's houses trying to 'sell' God are just as guilty of being contemptuous as those who engage in violent behaviour, since they both aim to achieve a similar goal.

I know that. I've spoken to Capn about it too, but there's not much to be done except for deleting the thread. I really just wanted to see if he'd be stupid enough to reply.

I agree with the other two, this is a very suspicious synthesis. If you can show that this isn't a means to produce illicit substances, we'd be happy to help. If not, I have to ask how on earth you thought pulling the proverbial wool over the eyes of the professional chemists who use this site would actually work?