what PCC can do?

R. A. Fernandes, P. Kumar / Tetrahedron Letters 44 (2003) 1275–1278


Before the studies of Corey and co-workers,1 the reactivity of PCC had been little investigated. PCC is well known to convert alcohols into aldehydes or ketones with high efficiency.2a This reagent also converts tertiary cyclopropyl carbinols into the corresponding , -unsaturated ketones,2b 1,4-dienes into dienones,2c,d hydroquinone silyl ethers into quinones,2e enol ethers toesters and lactones2f and oximes to ketones.2g Other known important conversions using this reagent are: (i)furan rings undergo oxidative ring expansion,3a (ii) 5-3 -tetrahydropyranyl ethers are oxidized to the corresponding carbonyl 4-3,6-diones,3b (iii) olefins are oxidized to carbonyl compounds via the oxidation of organoboranes.3c–g Furthermore, PCC is well known
for selective oxidation of steroidal allylic alcohols,4a oxidative cleavage of aryl substituted olefins,4b specific oxidative cleavage of allylic and benzylic ethers,4c oxidation of benzylic4d and active methylene compounds,4e oxidative cleavage of 1,4-dioxenyl carbinols to - hydroxy acids and -ketoacids,4f one-pot oxidation of glycals to lactams,4g cleavage of vicinal diols4h and modified oxidation of aldehydes to carbamoyl azides/ acyl azides or carboxylic acids.4i Thus, the varied and numerous oxidative reactions of PCC makes it a versatile oxidant in organic synthesis.5


references;
1. Corey, E. J.; Suggs, J. W. Tetrahedron Lett. 1975, 16, 2647–2650.
2. (a) Augustine, R. L. Oxidation; Marcel Dekker: New York, 1969; Vol. 1; (b) Wada, E.; Okawara, M.; Nakai, T. J. Org. Chem. 1979, 44, 2952–2954; (c) Wender, P. A.;
Eissenstat, M. A.; Filosa, M. P. J. Am. Chem. Soc. 1979, 101, 2196–2198; (d) Marshall, J. A.; Wuts, P. G. M. J. Org. Chem. 1977, 42, 1794–1798; (e) Willis, J. P.; Gogins, K. A. Z.; Miller, L. L. J. Org. Chem. 1981, 46, 3215–3218; (f) Piancatelli, G.; Scettri, A.; D’Auria, M. Tetrahedron
Lett. 1977, 18, 3483–3484; (g) Maloney, J. R.; Lyle, R. E. Synthesis 1978, 212–213.
3. (a) Piancatelli, G.; Scettri, A.; D’Auria, M. Tetrahedron Lett. 1977, 18, 2199–2200; (b) Parish, E. J.; Kizito, S. A.; Heidepriem, R. W. Synth. Commun. 1993, 23, 223–230; (c) Ramana Rao, V. V.; Devaprabhakara, D.; Chandrasekaran, S. J. Organomet. Chem. 1978, 162, C9–C10;
(d) Rao, C. G.; Kulkarni, S. U.; Brown, H. C. J. Organomet. Chem. 1979, 172, C20–C22; (e) Brown, H. C.; Kulkarni, S. U.; Rao, C. G. Synthesis 1980, 151–153; (f) Brown, H. C.; Kulkarni, S. U.; Rao, C. G. Synthesis 1979, 702–704; (g) Brown, H. C.; Rao, C. G.; Kulkarni, S. U.
Synthesis 1979, 704–705.
4. (a) Parish, E. J.; Schroepfer, G. J., Jr. Chem. Phys. Lipids 1980, 27, 281–288; (b) Narasimhan, V.; Rathore, R.; Chandrasekaran, S. Synth. Commun. 1985, 15, 769–774; (c) Cossy, J.; Bouzbouz, S.; Lachgar, M.; Hakiki, A.; Tabyaoui, B. Tetrahedron Lett. 1998, 39, 2561–2594; (d)
Rathore, R.; Saxena, N.; Chandrasekaran, S. Synth. Commun. 1986, 16, 1493–1498; (e) Bonadies, F.; Bonini, C. Synth. Commun. 1988, 18, 1573–1580; (f) Fetizon, M.; Goulaouic, P.; Hanna, I. Tetrahedron Lett. 1988, 29, 6261– 6264; (g) Rollin, P.; Sinay, P. Carbohydr. Res. 1981, 98, 139–142; (h) Cisneros, A.; Fernandez, S.; Hernandez, J. E. Synth. Commun. 1982, 12, 833–838; (i) Reddy, P. S.; Yadagiri, P.; Lumin, S.; Shin, D.-S.; Falck, J. R. Synth.
Commun. 1988, 18, 545–551.
5. Piancatelli, G.; Scettri, A.; D’ Auria, M. Synthesis 1982, 245–258.

reduction of ester to methane

1. LAH reduce ester to alcohol.

Then
1. two electron reduction
MsCl/TEA converts the alcohol to a leaving group. Then LAH or NaBH4/high temp will remove the MsO.
note: a more gentle condition: NaBH4/t-BuOH/DME refluxing temp will not touch nitrile.

2. One electron reduction
xanthate then aibn.
note: usually selectivity between sec-OH and tert-OH is good.

Hydrogenation of double bond

1. heterogeneous metal catalyst.

1. pd/c is better than pt. because it won't hydrogenate aromatic rings.
2. Benzyl ether and trityl ether can be kept by addition of nitrogen containing base (Py, TEA, ...), the selectivity is very good.
3. Benzyl ether reduced quicker in THF than in MeOH.
3. Ir black gives better facial selectivity than Pd/c, PtO2.
4. hydrogenation in polar solvents is quicker. AcOH>MeOH>EtOH>THF. But facial selectivity is worse.
5. trace of water can activate the metal surface. Good for both hydrogenation and benzyl removal.

2. homogeneous catalysts
wilkinson's catalyst, facial selectivity is bad.

3. hydrazine reduction.
active NH=NH generated by heating tosylhydrazine with base.
very useful when a gental touch is desired.
can reduce triple bond to double bond.

preparation of Dess Martin reagent

recently made about 50 g of it.
here is the detail.

1. oxone 2 eq. and 2-iodobenzylacid? 1 eq. mixed together with deionized water.
stirred at 70-73C for about 4 hr. during the stirring, the insoluable iodoacid will get into the water solution. Finally a nearly clear solution will be seen with some precipitation on the bottom. good stirring is necessary.

2. cool the temp down to 0-5C for 2hr, filter out the white precipitation. wash with acetone.
The ibx is potencially explosive, it is stable at rt and should be dried at rt and 1 atm.

3. pour in Ac2O and catalytic amount of psOH-H2O solid. heated to 80C for 3 hr, a clear solution resulted. cooled it down to 0-5 C, then liquid filtered. washed with ether.
also explosive, dried in vacuo briefly.
stored in freezer.

reduction of nitrile

DibalH.
reduce nitrile to aldehyde imine or amine.

LAH can also reduce the nitrile to imine . usually, low yielding.

alkene to alkyne

1. dibromination.
DCM. 0 C or -78C if you have bromine sensitive group( for example: benzyl ether)

2. 2 eq. Base.
strong base is needed.
LDA or KHMDS.
n-BuLi is not good.


note: if you have a heteroatom ( oxygen ) alpha to you dibromide, you can use weaker base to make it into alkyne (DBU)

What data you need to publish a new compound?

The following is what I did to characterize organic compounds for ACS publication.

Unknown compounds.
1. TLC Rf.
2. melting point ( for solid)
3. IR (5 or 6 typical peaks)
4. NMR (proton and jvert)
5. high resolution MS.
6. alpha D ( for optical pure compound)

known compounds
1. tlc
2. mp.
3. nmr.
4. alpha D.

How to put both 1H and 13C nmr into one page?

in topspin.
1. bring up your 1H nmr.
2. "edc2" to setup up your 13C nmr.
3. open xwinplot.
4. set up the proton layout. then add a new spectra, choose the data set to your 13C nmr.
5. print.

How to insert NMR spectra into word.

software: topspin(unix), microsoft word( windows).
use xwinplot to setup the layout, then
"print as file" the spectra as *.png file. (jpg is bigger sized, pdf can't be inserted into word)
then transfer the png file into windows., you can directly insert pic from file into word.
the spectra made this way is very clear (600 dpi),
and very small size (~50k each page).