Question

Cholesterol is an essential ingredient of cell membranes. In atherosclerosis, it accumulates in plaque on artery walls and gallstones can be nearly pure cholesterol. About 85% of the roughly 150 g of cholesterol in a healthy human body is found in cell membranes. The structure below is the enantiomer of natural cholesterol Using the structure and image below, determine the conformation of each of the designated substituents (Use the carbon atom numbering from the image on the left.) CH3 На 4 H Ha ball & stick #-| +labels OH at C3: Hb, at C4: Ha at Cll:

Answer 1

Show the stereochemistry of cyclohexane at each chiral center in wedge and dash form Key points to convert substituted cyclohexane from chair conformation to ring conformation: (i [1,2] and [1,4] diaxially and di-equatorial are trans conformations, (ii [1,2] and [1,4] axial-equatorial are cis conformations (iii [1,3]- diaxially and di-equatorial are cis conformations (iv) [1,3] axial-equatorial are trans conformations, R Equitoroial bond Axial bond Flliping the ring R. R/. R The stereochemistry at each mentioned centers of cholesterol are as follows: н НаС НС Н н HOI Н н 11 Нь НО На Н Answers: (i OH at C3 equatorial (ii) Нь at C4 aхіal (ii Ha at C11 equatorial