fit <- lm(R1 ~ R2)

Call:
lm(formula = R1 ~ R2)

Residuals:
      Min        1Q    Median        3Q       Max
-0.128139 -0.016528  0.000349  0.017806  0.125109

Coefficients:
            Estimate Std. Error t value Pr(>|t|)
(Intercept) 0.003785   0.001884   2.009   0.0453 *
R.2         0.949923   0.043904  21.636   <2e-16 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

fit["coefficients"]

$coefficients
(Intercept)   R2
0.003785144 0.949923219