Organic Chemistry

A 1-butyne + 2HCI 2,2-dichlorobutane

lkynes are hydrocarbons

that contain a carbon–carbon

triple bond. Because of its

triple bond, an alkyne has four fewer

hydrogens than the corresponding alkane. Therefore, the general molecular formula

for an acyclic (noncyclic) alkyne is and that for a cyclic alkyne is

There are only a few naturally occurring alkynes. Examples include capillin, which

has fungicidal activity, and ichthyothereol, a convulsant used by the Amazon Indians

for poisoned arrowheads. A class of naturally occurring compounds called enediynes

has been found to have powerful antibiotic and anticancer properties. These com-

pounds all have a nine- or ten-membered ring that contains two triple bonds separated

by a double bond. Some enediynes are currently in clinical trials.

A few drugs contain alkyne functional groups, but they are not naturally occurring

compounds. They exist only because chemists have been able to synthesize them. Their

trade names are shown in green. Trade names are always capitalized and can be used for

commercial purposes only by the owner of the registered trademark (Section 30.1).

CnH 2 n- 2 , CnH 2 n- 4.

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6

Reactions of Alkynes •

Introduction to

Multistep Synthesis

O

C

parsalmide

an analgesic

Parsal

Sinovial

Norquen

Ovastol

NH(CH 2 ) 3 CH 3

CH

H 2 N

OCH 2 C

CH 3

mestranol

a component in oral contraceptives

CH 3 O

H 3 C OH

pargyline

an antihypertensive

Eudatin

Supirdyl

CH

C CH

CH 2 NCH 2 C

O

CH 3 CCC C

capillin

C CH 3 CCC C

ichthyothereol

C C C

C

O

H

HO

H

R^4

R^5

R^1

R^2

R^3

an enediyne

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