Organic: lanosterol Biosynthetic Cyclization

[whatlifeforme]

This is a tough one!

Shown is the biosynthetic cyclization of oxidosqualene catalyzed by oxidosqualene cyclase (OSC) leading to lanosterol as the final product.

The reaction starts with a protononation step as shown. Indicate the flow of electrons after the initial protonation step leading to the product given.

Indicate the flow of electrons by starting your curved arrow at a bond or unshared electron pair.
In this question, the endpoint of your curved arrow will be an atom.
You should be able to find appropriate hot spots in the drawing.

[PLAIN]http://owl.cengage.com/mediaarchives/OrgChemJuly2009/Image/B7.28b.gif

 

[sjb-2812]

This is a tough one!

Shown is the biosynthetic cyclization of oxidosqualene catalyzed by oxidosqualene cyclase (OSC) leading to lanosterol as the final product.

The reaction starts with a protononation step as shown. Indicate the flow of electrons after the initial protonation step leading to the product given.

Indicate the flow of electrons by starting your curved arrow at a bond or unshared electron pair.
In this question, the endpoint of your curved arrow will be an atom.
You should be able to find appropriate hot spots in the drawing.

[PLAIN]http://owl.cengage.com/mediaarchives/OrgChemJuly2009/Image/B7.28b.gif[/QUOTE]

One way to start might be to count the hydrogens on each carbon?