Concept explainers
(a)
Interpretation:
The curved arrows for each step of the mechanism must be drawn and the sequence of arrow pushing patterns must be identified.
Concept Introduction :
The curved arrow shows the electron flow; and thereby, it shows bond breaking and new bond formation. The alpha hydrogen of
(b)
Interpretation:
For the conversion of 4 to 5 the electrophilic and nucleophilic centers must be identified with the help of resonance.
Concept Introduction :
Electrophilic centers are those where there is low electron density. Nucleophilic centers are those where there is higher electron density.
(c)
Interpretation:
Configuration of the newly formed chiral center during conversion of 4 to 5 must be determined. Why the other possible configuration is not observed must be explained.
Concept Introduction :
The configuration of a chiral center depends on the three dimensional orientations and priorities of different groups. Priorities of those groups can be determined using CIP (Cahn-Ingold-Prelog) priority rules according to which higher is the
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EBK ORGANIC CHEMISTRY AS A SECOND LANGU
- The standard procedure for synthesizing a compound is the stepwise progress toward a target molecule by forming individual bonds through single reactions. Typically, the product of each reaction is isolated and purified before the next reaction in the sequence is carried out. One of the ways nature avoids this tedious practice of isolation and purification is by the use of a domino sequence in which each new product is built on a preexisting one in stepwise fashion. A great example of a laboratory domino reaction is William S. Johnsons elegant synthesis of the female hormone progesterone. Johnson first constructed the polyunsaturated monocyclic 3 alcohol (A) and then, in an acid-induced domino reaction, formed compound B, which he then converted to progesterone. A remarkable feature of this synthesis is that compound A, which has only one stereo-center, gives compound B, which has five stereocenters, each with the same configuration as those in progesterone. We will return to the chemistry of Step 2 in Section 16.7 and to the chemistry of Steps 3 and 4 in Chapter 19. In this problem, we focus on Step 1. (a) Assume that the domino reaction in Step 1 is initiated by protonation of the 3 alcohol in compound A followed by loss of H2O to give a 3 carbocation. Show how the series of reactions initiated by the formation of this cation gives compound B. (b) If you have access to a large enough set of molecular models or to a computer modeling program, build a model of progesterone and describe the conformation of each ring. There are two methyl groups and three hydrogen atoms at the set of ring junctions in progesterone. Which of these five groups occupies an equatorial position? Which occupies an axial position?arrow_forwardAlcohols are important for organic synthesis, especially in situations involving alkenes. The alcohol might be the desired product, or the OH group might be transformed into another functional group via halogenation, oxidation, or perhaps conversion to a sulfonic ester derivative. Formation of an alcohol from an alkene is particularly powerful because conditions can be chosen to produce either the Markovnikov or non-Markovnikov product from an unsymmetrical alkene. Using your reaction roadmap as a guide, show how to convert 4-methyl-1-pentene into 5-methylhexanenitrile. You must use 4-methyl-1-pentene and sodium cyanide as the source of all carbon atoms in the target molecule. Show all reagents needed and all molecules synthesized along the way.arrow_forwardOrganotin compounds play a significant role in diverse industrial applications. They have been used as plastic stabilizers and as pesticides or fungicides.One method used to prepare simple tetraalkylstannanes is the controlled direct reaction of liquid tin(IV) chloride with highly reactive trialkylaluminum compounds, such as liquid triethylaluminum (Al(C2H5)3). 3SnCl4 + 4Al(C2H5)3 3Sn(C2H5)4 + 4AlCl3 In one experiment, 0.230 L of SnCl4 (d = 2.226 g/mL) was treated with 0.396 L of triethylaluminum (Al(C2H5)3); d = 0.835 g/mL). If 0.335 L of tetraethylstannane (d = 1.187 g/mL) were actually isolated in this experiment, what was the percent yield?arrow_forward
- 1. There are several isomeric alkanes of molecular formula C6H14.Two of these exhibit the following 1H-NMR spectra. Propose a structure for each of the isomers. Isomer A: δ = 0.84 (d, 12 H), 1.39 (septet, 2H) ppm Isomer B: δ = 0.84 (t, 3 H), 0.86 (s, 9H), 1.22 (q, 2H) ppmarrow_forward15.34 Coriolic acid, isolated from the hearts of cows, is of interest because of its ability to transport calcium ions through membranes. It was synthesized by the following sequence of steps. Supply structural formulas for the compounds designated by letters. HO(CH₂), OH H HC C-C F C-CH₂OH H C+B D HBr (48%) (1 equiv) H₂O H₂O+ cold CH,(CH₂),CH,MgBr (2 equiv) diethyl ether tetrahydrofuran E A CrO₂, H₂O H₂SO acetone Li*NH, (2 equiv) NH,(liq) tetrahydrofuran oxidizing agent similar to NH,C, HO G B H CrO,CI Farrow_forwardSpirocyclic compounds, such as compound 3, are made and used by insects for the purposes of communication. The first step of a synthesis of compound 3 involves treatment of (S)-1,2-epoxypropane (compound 1) with lithium acetylide, followed by acid workup, to give compound 2, as shown below (J. Org. Chem. 2005, 70, 3054-3065). Identify the structure of compound 2 and provide a mechanism for its formation. (Hint: The carbon-lithium bond reacts in a way that is similar to the carbon-magnesium bond of a Grignard reagent.) 1 13.17 a 1) Li—= 2) H₂O+ нас!!!!!! C5H8O Edit Drawing 2 Ž Modify the given structure of the starting material to draw the major product. an 3arrow_forward
- Organotin compounds play a significant role in diverse industrial applications. They have been used as plastic stabilizers and as pesticides or fungicides. One method used to prepare simple tetraalkylstannanes is the controlled direct reaction of liquid tin(IV) chloride with highly reactive trialkylaluminum compounds, such as liquid triethylaluminum (Al(C2H5)3). 3SnCl4 + 4AI(C2H5)3 →3Sn(C2H5)4 + 4AlCl3 In one experiment, 0.160 L of SnCl4 (d = 2.226 g/mL) was treated with 0.346 L of triethylaluminum (Al(C2H5)3): d = 0.835 g/mL). What is the theoretical yield in this experiment (mass of tetraethylstannane, Sn(C2H5)4)? If 0.257 L of tetraethylstannane (d= 1.187 g/mL) were actually isolated in this experiment, what was the percent yield?arrow_forwardWrite down the explicit structures of A, B, C and D in accordance with the reactions given in the synthesis plan, which shows the synthesis of D, a pheromone of moth.arrow_forwardIII. Carrow_forward
- 3. Answer all parts a. Give the structures of compounds A, B and C in the reactions below. i. H,SO4. Compound A ii. () NaOH, 350°С, 200 atm (2) Н,0* Compound B Compound C + Br ÓHarrow_forwardCompound 6 is a driloderensin, a surfactant molecule that helps prevent protein precipitation in the gut of an earthworm during digestion. Starting with furan and any organic or inorganic reagents, propose a synthesis of 6. ? 6 SO3Harrow_forwardII. Alcohols in synthesis A. What are the strategies for the synthesis of alcohols by nucleophilic substitution reactions using halide leaving groups with hydroxide as a nucleophile? How do you predict possible by-products that could arise from this strategy? How do you use the less acetate nucleophile followed by treatment with NaOH to avoid by-products?arrow_forward
- Organic ChemistryChemistryISBN:9781305580350Author:William H. Brown, Brent L. Iverson, Eric Anslyn, Christopher S. FootePublisher:Cengage Learning