reductive deoxygenation of vinlyl or aryl triflate

Some conditions:

1. pd(PPh3)4/Bu3SnH/THF.
works for vinyl triflate.

2. pd(OAc)2/DPPF/Formic acid/TEA/Bu3SiH/DMF, 50C
works for electron-rich aryl triflate.

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proposal of synthesis of namenamicin

Namenamicin is a enediyne.
the construction of the sulfur-containing quartery center is the critical part of the synthesis. This proposal uses a thionium ion to directly form the quartery center which can lead to the desired structure in an efficient way.

proposal of synthesis of dictyolactone

1.The target is quite an interesting molecular.
2. This proposal mainly aims at the application of C-H insertion in total synthesis.

How to convert indole to tryptamine ?

1. POCl3-DMF to make the indole aldehyde,
2.nitromethane to make unsaturated nitro indole.
3. LAH reduction to give you tryptamine.

to save one step, step 1 and 2 can be made into one step:
TFA, (CH3)2N-CH=CH-NO2, DCM to make the unsaturated nitro indole.

to increase the functional group compatibility of this sequence,
the LAH reduction step can be replaced by a 2 step sequence:
1. NaBH4/SiO2 reduction to take off the double bond.
2. Fe/AcOH reduction to convert the nitro group to amine.

How to reduce 2-oxyindole ?

1. BH3. 0C.
slow reaction, low yielding, but can tolerate many functional groups, like ester.
can over reduced to indoline.

2. LAH
of course, amide can be reduced.

3. triflation first, then Pd/Et3SiH remove triflate.

4. lawesson's reagent to convert oxygen to sulfur, then reduce it by
Raney Ni.

5. some reducing reagent (red-al, super hydride...) under the help of acid (TFA, BF3-OEt2...)

How to prevent N-Cbz from falling off in hydrogenation condition ?

N-Cbz is sensitive to H2/pd/c even in basic condition (TEA).
Known methods to prevent N-Cbz from falling off when doing hydrogenation reactions are not many.

1. Pd/c (en), H2, THF by Kosaku Hirota
pd/c (en) is pd/c deactivated by ethylenediamine. It is developed for chemoselective hydrogenation of reducible functionalities such as olefin, acetylene, nitro, azide, aromatic bromine or benzyl ester moieties, in the presence of O-Bn or N-Z protective
groups.
alkyl N-cbz is stable while double bonds are saturated.
aryl-N-cbz is unstable under this catalyst.
H. Sajiki, K. Hattori and K. Hirota, J. Org. Chem., 1998, 63, 7990.

2. Pd(OAc)2, DPPF,TEA, dmf,formic acid
Can do deoxygenation of phenol by OTf in the presences of N-Zbz.

3. squaric acid derivative/pd/c/H2
works ok, can saturate double bond without touch n-cbz.

4. pd/c/ph2s/H2
also can saturate double bond without touching n-cbz.

5. Pd(OAc)2, DPPF, TEA, dmf,formic acid, Et3SiH
works for deoxygenation of phenol triflate in the presense of N-Cbz.

Note:
1. pd/c(en) was tried. but n-cbz falled off quickly.
2. dppe/pd/formic acid method is OK.
3. ph2s/pd/c/h2 didn't touch N-cbz in my hand. but can't do deoxygenation of a phenol.